ORION Trapezium, October 2025, Vol. 51, Issue 10.

ORION | Trapezium Vol. 51, Issue 10 https://zenodo.org/records/17316280 Fri 10 Oct 2025 JD2460959 . A Monthly Publication of the ORION Astronomical Society This is an image of the planet Saturn, showing its moon Titan and Titan’s shadow as they transit across the planet. This image was captured by John Cliff at his home observatory 5.8 km ESE of TAO, early on the morning of 20 Sep 2025. For more details, see the Astrophotography section inside. . Table of Contents 3 4 6 8 14 22 23 24 29 30 31 37 42 47 50 57 61 64 65 68 70 71 73 74 75 77 Ab initio Page Three Astronomy: “The Search for Alien Life” ……..………..……………..……… About ORION and TRAPEZIUM ……..……….……………...…………...……................ Messages from ORION President’s Message - Don Spong …………………………………….....….……..……..… TAO Director’s Message / Observatory Way - David Fields .…………………....……… ORION Board Meetings ElCantarito - Rob Fowler ……………………………..…….….. ORION Monthly Meetings ORION Monthly Meeting Format ….……………..……………….…….….……....……… ORION Meeting 15 Oct 2025: Astronomy at the Obed WSR - Joshua Gray …….…… ORION Last Month: Groundwater Tracers - Gareth Davies …….…….……….....….… Events and Calendars, Sky Maps and Occultations Star, Moon, Comet and Meteorgazing at TAO in 2025 ……….………..….…..….….... TAO Public Stargazing: A Note Regarding Scheduling and Access in 2025 ..…..……. Public Stargazes in Oct & Nov 2025; TAOCalendars…………….…...…………….……. Public Stargaze of 20 Sep 2025 ……………………………………………………………… Occultation of TYC 2436-00120-1 by the asteroid 337 Devosa - Richard Piety ……... A Night in Cloudcroft - Ted Barnes………………………..………….............................. The Stargazey Events of Thu 02 Oct 2025 - Ted Barnes ………………………………… Public Stargaze of 04 Oct 2025 ……………………………………………………………… The Evening Sky Map / Oct 2025 .…………………………….………….……..………...... Astrophotography Titan and shadow transiting Saturn - John Cliff …………..……….…………….……… The Veil Nebulae - Don Spong …………………………………..…….…………….……… Appendices Astronumerology ……………………………………..…………………………………..…… The 80 Brightest Stars ………………………………….……………………………..……… Notable Star-Pair Angles …………………………..…………………………….…..……… Exeunt Poetica .………………………………………….…..………………….….……………..…… ORION and TAO General Information (and links) ………………………………..……... Trapezium back issues online …………………………………….……….……..…...…..… Fin du Journal …….…………………………………………………………………....…….. Page Three Astronomy The ORION Astronomical Society is a science and astronomy group founded in April 1974 by scientists from the United States Department of Energy facilities at Oak Ridge, Tennessee. We primarily serve the communities of Oak Ridge and Knoxville and the counties of Anderson, Knox, and Roane. ORION’s mission is to support scientific research, teaching, and astronomical activities in East Tennessee. We hold monthly public meetings at the Oak Ridge RSCC Campus, and are active at TamkeAllan Observatory (TAO), hosting public events, sharing knowledge of the skies, and helping to provide intellectually stimulating programs. ORION works to share the wonders of the cosmos and the culture of science. ORION members include scientists, engineers, technicians, IT experts, artists, students, and others with varied talents and expertise. Over half of ORION members own telescopes, many are amateur radio operators, and some have expertise in astrophotography. ORION has working relationships with several organizations, including museums and other amateur astronomy groups. Membership is open to individuals who will actively contribute their time and ideas. The annual membership fee is $20, and student discounts are available. There is no charge for our newsletters and publications, or for participation in most ORION activities. TRAPEZIUM is a monthly publication of the ORION Astronomical Society. The issue date is the Friday preceding the monthly ORION meeting, chosen to provide timely information regarding the planned Program. From March 2025 we will be working towards issuing a somewhat shorter version of the Trapezium, which will still include important information regarding the monthly ORION presentation, as well as dates and other information regarding Public Stargazes and other notable events relating to ORION and TAO. Regarding the contents of this revised Trapezium, we have already concluded that some components, such as a separate Astrophotography section, are so important for a publication on amateur astronomy that one really cannot justify excluding them. ORION Board and Officers: President: Don Spong VP and Program Chair: David Fields Social Chair: Noah Frere Secretary: Rob Fowler Treasurer: Bob Edwards Editor: Ted Barnes Astrotechnologist: Rob Scott Videographer: Rob Fowler Obed Site Outreach: Joshua Gray. 4 Messages from ORION We’ve recently had some successful stargazing nights with favorable weather at Tamke-Allan (September 20, October 2 and 4). Thanks to the weather gods and all those who participated. There’s been a lot of astronomy in the news recently related to three comets: 3I/Atlas, C/2025 R2 (SWAN), and Lemmon (C/2025 A6). 3I/Atlas, the interstellar visitor, continues to attract attention due to speculation that it might be an alien probe. This has been fueled by Abraham Loeb of Harvard University and collaborators at the Initiative for Interstellar Studies in the UK. They’ve written a paper on arXiv: 2507.12213 exploring the anomalous photometric and astrometric characteristics of 3I/Atlas and then going on to describe the orbital changes it could make while passing behind the sun if its intention were to intercept the Earth (which could come in late November/early December); so hold on to your hats! However, in the conclusion they write: “By far the most likely outcome will be that 3I/ATLAS is a completely natural interstellar object, probably a comet.” In any event there will potentially be some viewing opportunities for 3I/ATLAS in the early morning hours of early November, but it will be significantly fainter than C/2025 R2 (SWAN) (by 190 times) or Lemmon (C/2025 A6) (by 120 times). In October the full moon (known as the Harvest Moon) is October 6 and the new moon is October 21. As mentioned above there are several comets around. Lemmon (C/2025 A6) is visible currently in the early morning hours, and is well positioned high in the sky. It is approaching a brightness level soon where it will be naked eye visible. C/2025 R2 (SWAN) is an evening comet, but is low in the sky (about 17 degrees above the horizon). 3I/Atlas is dim and about to go behind the sun, but there may be better opportunities to image it in November. Planets that are currently in good position are Saturn, Neptune, and Uranus. Jupiter doesn’t show up until around 1am. There is a meteor shower, the Orionids, coming up October 20, 21. Fortunately, this is the same time as the new moon, so viewing conditions should be ideal, weather permitting. Some of the deep-sky objects of interest this month are: 6 President’s Message (cont.) - Don Spong M57, the Ring Nebula in the constellation Lyra, about 2500 ly away; NGC 7000, the North American Nebula in Cygnus, also about 2500 ly away; NGC 2826, the Blinking Planetary Nebula, also in Cygnus, about 2000 ly away; NGC 7293, the Helix Nebula in Aquarius, about 650 ly away; the star cluster M15 in Pegasus, about 35,700 ly away, M31, the Andromeda galaxy, in Andromeda, and about 2.2 Mly away; and NGC 7331, Stephan’s quintet, also in Andromeda, about 50 Mly away. 7 President’s Message (cont.) 8 David Fields October 2025 The photo on the left shows our new road sign for Roane State’s Tamke-Allan Observatory (TAO). Traveling West on Caney Creek Road from Roane County Park, the sign appears on the left just after crossing Joiner Hollow Road. TAO offers Public Stargazes to the community on the 1st and 3rd Saturday of each month, weather permitting. Our usual schedule for the summer is to open at 8:30 pm and continue to nominally 10:30 pm -- later when the sky and attendance encourage this. Opening time changes according to the season, and a good guide is to arrive at the observatory about sunset, when weather is encouraging. These Stargazes are supported by local astronomy clubs, especially ORION members and friends, and benefit our students and community. Our TAO Stargazes are usually well attended, with a full classroom of visitors for evening astronomy lectures. TAO Public Stargazes and Special Events TAO Director’s Message / Observatory Way : What are rulers and Sky Rulers? Where do we carry them? A ruler is a tool for measurement of linear distance. Measurement can be a tool for understanding. We can define a Sky Ruler as a tool for measuring angular separation of objects in the sky. Let’s explore the need, the history of celestial angular measurement, and possible design for a modern Sky Ruler. In general, a ruler is useful only when it is in the hands of the user. For a hiker with a map, the ruler is in his hand with his map and compass. For a designer or engineer, the ruler is on his desk. For a medical technician, the same. The ORION Sky Ruler This photo shows a plastic ruler that ORION gave to RSCC students and ORION members a few years ago, together with another of my favorite astronomy rulers: Astronomy Rulers For an astronomer, the sky ruler must be close at hand – in his/her pocket, or hidden on a reticle in his telescope eyepiece, or be part of a computer program. Once a telescope is aligned with the sky the astronomer may rely on the computer for many things, but if there is no computer, the astronomer needs the Sky Ruler in his pocket So, how may we obtain or design such a ruler? And how do we get it into the hands of ORION members and TAO students? The Sky Ruler should also present physical constants, show linear measurements (inches and cm), be inexpensive so we can give away as many as we like, identify ORION as a research-oriented group of enthusiastic, fact-oriented astronomers, and delight ORION members and students. This was the challenge I posed to our ORION board last Monday. We’re still thinking about this, so let us know your suggestions. Meanwhile, here are some background thoughts. Observatory Way (cont.) The ORION ruler (above) fulfilled several purposes. It was a nice Christmas gift to ORION members and students, plus it introduced students in my Astronomy classes to the idea that ‘measurements’ are important. It also introduced the metric system. It was an example of how ORION helps the college, in additional to helping the students with astronomy, and introducing astronomy and the night sky at our TAO stargazes. I wished many Stardate: 2025.06.02 In attendance were Don, David, Bob, Art, Juan, Kevin and Noah (and Sunny). We met early at the library to discuss the current and new display box. Discussed meeting again, tomorrow (Tuesday). David suggested Wednesday night 8:30pm as the next Friendship Stargaze. Kevin suggested meeting at TAO to look at the Meade's encoder. Noah suggested reaching out to Gareth Davis to see if he has any potential acquaintances for another lecture. Don asked about the new dome project. David responded with a tale of woe regarding the Roane purchasing project. Stardate: 2025.06.09 In attendance were Don, David, Art and Rob (joined by John Rather). David purchased 2 coin cells for the Celestron CGM mount. He also purchased a few ferrite cores to suppress noise from the power supply. Ted expressed an interest in having help with this months Trapezium. Discussed the new optical telescope coming online in the Atacama Desert. Briefly mentioned the library displays and Oak Ridge street lighting. Noah mentioned that Gareth Davis can give the next lecture. Stardate: 2025.06.16 In attendance were Don, Kevin, Art and Rob. Rob showed his submission for the AMSE poster. Kevin & Don discussed PixInsight. We confirmed Kevin is speaking this month. Kevin discussed the Astronomical League and it's various programs, and contests for various achievements. Stardate: 2025.06.23 Due to crowding at the table, no notes were taken. In attendance were Don, David, Ted, Art, Kevin and Robert. Stardate: 2025.06.30 In attendance were David, Ted, Art, Kevin, and Rob. Don sat in for a short while. Ted & Rob discussed results of the occultation via a new process. Kevin presented a new ORION Logo. Kevin announced he will be moving out of the immediate area. 16 ORION Board Meetings (cont.) Stardate: 2025.06.30 David presented Kevin with a gift ORION T-Shirt. David brought up shop type measurements he intends to do on the Meade. The group went on discuss various theoretical topics. Mention of 4 visitors who showed up at TAO and new member Kevin Wilson David brought up calendar access. Discussed problem with rotation of glow dome lid. Watch for migration of wheel axels. One axel migrated in and caused the lid to bind. Stardate: 2025.07.07 In attendance were Don, Ted, David, Art, Rob and visitor John Rather. Conversations opened with Ted discussing digitizing the occultation substacking project. David discussed a lightstrip project and possible application in the dome. Ted collected info for this month's Trapezium. David discussed attendance at the Sat July 5 Public Star Gaze, was 12, give or take. David discussed the testing we did on the Meade and saw no alignment errors. Stardate: 2025.07.14 In attendance were David, Ted, Art and Rob. Ted shared some mathematical analysis of the recent occultation data. David brought up potential dates for the next Friendship Star Gaze. We discussed the next ORION lecture and whether to zoom it or not. We discussed possibly having a news feature at ORION lectures. Stardate: 2025.07.21 In attendance were David, Don, Ted, Art, Rob... and guest John. Dave led the discussion with Rob's absence. Dave mentioned that Saturday night’s public star gaze was successful, with around 8 visitors. We discussed the recent lecture and the unplanned move to the computer classroom. The general consensus is that it went well. Dave will be away on August 2nd, the next star gaze. Ted brought up details of participation in the Tuesday night / Wednesday morning occultation. Stardate: 2025.07.28 In attendance were David Fields, Ted Barnes, Art Alison and Rob Fowler We will probably have a public star gaze at TAO on 8/2/2025, public or private depending on weather and Noah's decision. 8/12/2025 Perseid meteor shower a probable star gaze. 17 ORION Board Meetings (cont.) Stardate: 2025.07.28 Our Library display will expire soon. David will inquire if we can keep it another month or if we need to clean it out this month. If it has to come down, Ted & Rob have agreed to remove the contents. Stardate: 2025.08.04 Present were Don, Ted, Rob, Art and guest John Rather. Ted shared his most recent results and submission to IOTA that we have been re-evaluating. Don won’t be present for the August ORION meeting. We believe John Cliff is August's speaker. We discussed various lightning phenomenon We also discussed the Big Bang theory and John Rather's book. Stardate: 2025.08.11 Present were Don, Ted, David, Art, Rob and guests Richard Piety and John Rather. Ted reported on some of his recent results with IOTA’s python scripts and graphing. Rob reported on visiting Lily Bluff's Star Party at Wartburg, where he met Joshua, Gareth and Owen. Don told us of a new 16 bit color astro camera he just bought, a ZWO ASI2600MCP. John told us of an experience with a pro telescope. Richard just bought a QHY174M-GPS camera for recording timed asteroid occultations. We discussed weather regarding the Perseid meteor / stargaze, 8:30pm Tuesday, but the weather is deteriorating. There is a possible occultation on 8/23/25. Star date: 2025.08.18 In attendance were Ted, David, Art, Rob and guests John Rather and Richard Piety. David spoke to Courtney at AMSE about our ORION display. We have been invited to keep it set up for a while longer. We discussed possibly tracking 3I/ATLAS to get a pic, having an unscheduled observation evening. Star Date: 2025.08.25 In attendance were Dave, Ted, Richard and Rob. Ted shared the results of the recent asteroid occultation. David visited the K-25 interpretive center and described the layout. He said they are interested in us bringing a star party to that location. David noticed that one of the new pads in collecting water. Rob suggested a modified a port-a-potty as a camouflage telescope cover. Calling it "Astro-Johnny: Smelling like Roses!" 18 ORION Board Meetings (cont.) Star Date: 2025.09.01 In attendance were David Fields, Ted Barnes, Art Alison and Rob Fowler. And visitor David Allred. David Fields fixed the internet with at TAO and treated several ant colonies. The skies were good from 9pm to Midnight. Discussed an upcoming eclipse in Sydney Australia in 2 years. Ted spoke to the programmer of Occult Watcher [Hristo Pavlov] who helped him troubleshoot a bug. IOTA Annual meeting is next week on zoom. Star Date: 2025.09.08 In attendance were David Fields, Ted Barnes, Rob Fowler, Don Spong, Art Alison and Richard Piety. We has a successful Moon-gaze at TAO last night. Ted discussed his occultation studies. He was successful with one last night Sunday 2025.09.07. Richard attempted it too but has not analyzed his results yet. We had a new guest last night, Art’s friend Deirdre Akin. She joined the astroluncheon as well. Star Date: 2025.09.15 In attendance were David Fields, Ted Barnes, Don Spong, Rob Fowler and Richard Piety. We discussed concerns over who is coordinating speakers going forward. Tentatively, we believe Gareth Davies is our September speaker. We discussed news about the cosmic interloper 3I/Atlas and new spectral data. 19 ORION Board Meetings (cont.) ORION Board Meeting at the ElCantarito Mexican Restaurant, Oak Ridge, Mon 22 Sep 2025. L to R: Ted Barnes, David Allred, David Fields, Richard Piety, Rob Fowler, and Gareth Davies. Star Date: 2025.09.22 In attendance were David Fields, Ted Barnes, Robert Fowler, Richard Piety and guest, David Alred. Gareth Davis, Art Allison, and Don Spong arrive later. Ted and Richard discussed results of a recent occultation. Richard caught 2 new occultations recently. David expressed concerns over the success of last Saturday's Stargaze. He felt distracted and so thought it did not go well. But several of us thought it went very well. Gareth Discussed cosmic interloper 3I/Atlas, and its tail having recently turned green. Richard Piety confirmed that the ORION website is badly out of date. To support Public Star gazes, David discussed having teams of 2 to operate the Meade. Gareth talked about an astrophysicist, David Butler, who has a Youtube channel. Star Date: 2025.09.29 In attendance were Don, Ted, David, Richard, Art and Robert. Ted told us about his visit to New Mexico and the skies at Cloudcroft. David asked about an abstract for October’s guest speaker, Joshua from OBED. We discussed possibly meeting at TAO on Wednesday or Thursday. Star Date: 2025.10.06 In attendance were David Fields, Don Spong, Ted Barnes, Rob Fowler & Art Allison. David suggested we create something as a giveaway to members and students. He suggested a plastic ruler to help people understand angles. He also discussed making a custom planisphere. We discussed using Night Sky Network to coerce dues compliance. Art took up the challenge of creating a new giveaway / print project. Although this month’s speaker is confirmed, no details have been communicated. Etymology needed for the expressions “cattiewumpus” and “whackadoodle.” ORION Board Meetings (cont.) ORION Monthly Meetings ORION Monthly Meeting Format Meeting Venue: City Room (A-111), just inside the main entrance, Coffey/McNalley Bldg., Oak Ridge Campus, Roane State Community College. 7:00 pm Eastern, 3rd Wednesday of each month. Our monthly meetings (except for December, a dinner) generally proceed as follows: •Welcome •Announcements •Invited Presentation and Discussion •Awarding of the Mug •Astrophotography / Special Presentations The nominal start time is 7:00 pm Eastern, on the 3rd Wednesday of the month. The beginning of the meeting will usually include announcements of general interest. Meetings typically continue until around 9:00 pm. Please plan to stay until the end. Hopefully we will all enjoy the astrophotography and other special topics discussed in the latter part of the meeting. Remote Viewing: A live Zoom session will usually be open during the ORION Monthly Meeting, at the link: https://us02web.zoom.us/j/88528735960?pwd=KzY4bnBHcjlhTzg3L3pOcjY0TFovUT09 or https://bit.ly/42apGxX Meeting ID: 885 2873 5960 Passcode: 716689 22 23 O R I O N October 15 P r o g r a m Title: Astronomy at the Obed WSR Speaker: Joshua Gray Park Ranger & Night Sky Coordinator Obed Wild & Scenic River Abstract: As a full-time ranger with the National Park Service, Josh wears many hats to serve the public. Examples of the duties he is in charge of include: •Operates the visitor center in downtown Wartburg, TN, providing information to park visitors 7 days a week. •Providing night sky programs and conducting meetings/research with Dark Sky International. •Collaborates with Big South Fork, Manhattan Project, and Frozen Head State Park rangers for festivals, programs, and other events. •Speaks to students at Morgan County Schools for career days, STEM nights, and other educational events. When he's not at work, he likes to spend nights at home with his wife Bergen, and their rambunctious 10 month old dog, Jett. He loves to spend time on Watts Bar Lake with his in-laws, and loves watching hockey. His talk will focus on the educational opportunities that Obed is providing to the public each and every month, especially highlighting the attendance of night sky programs. He will also give an update on the status of getting Big South Fork certified as a international night sky park, and the continued cooperation with Frozen Head State Park and Pickett C.C.C. Memorial State Park. 24 ORION Last Month – 17 Sep 2025 ORION President Don Spong opens the 17 Sep 2025 ORION Monthly Meeting. 25 ORION Last Month (cont.) The Lightest and Heaviest Elements and their Isotopes as Powerful Groundwater Tracers - Gareth Davies Our featured speaker for the ORION Presentation on 17 Sep 2025 was Gareth Davies, who earlier this year (16 Apr) had given an ORION presentation on “The Younger Dryas Cold Event” of 12.9 kyrs BP, which has a possible attribution to a cosmic impact. Is his Sep 2025 presentation Gareth discussed the history of and recent results in using tracers to determine subsurface water flow. The audience was clearly enthused by this presentation, which had considerable ORNL relevance, and was entertained by the many surprising results reviewed in this talk. The audience for Gareth’s 17 Sep ORION Presentation. TAO Calendars Jan-Jun 2025; Aug & Sep 2025 The principle public events for visitors at TAO are the Public Stargazes, held at TAO during 2025 on the 1st and 3rd Saturday of each month. These are listed in the “Public Fixed Events” TAO Calendar for six month periods, currently Jul-Dec 2025. These appear on the page following. Additional notable events will be included in monthly “Special Events” TAOCalendars. These include public events that do not have a fixed date long in advance, such as the International Friendship Stargaze in Oak Ridge, and special TAO events such as Asteroid Occultations, Meteor Showers, Full Moonrises, Lunar (and other) Eclipses, Comet Watches, and perhaps the occasional musical event. These “Special Events” calendars for the current and subsequent months appear after the six-month “Public Fixed Events” calendar. The facilities in the TAO buildings onsite will be open to the public during the “Public Fixed Events,” and will also usually be available when TAO is open to the public for some of the “Special Events.” Please inquire regarding whether TAO will be open to the public for any “Special Event” you may wish to attend, since some may be restricted. We will of course always try to accommodate enthusiastic visitors. We recommend checking a TAO website such as http://www. roanestate.edu/obs before visiting, to confirm that listed events will proceed as planned; weather conditions for example may require a cancellation or change of date. 32 date event details start end Sat 04 Jan 2025 1st Sat Stargaze 7:00 pm 10:00 pm Sat 18 Jan 2025 3rd Sat Stargaze 7:00 pm 10:00 pm Sat 01 Feb 2025 1st Sat Stargaze 7:00 pm 10:00 pm Sat 15 Feb 2025 3rd Sat Stargaze 7:00 pm 10:00 pm Sat 01 Mar 2025 1st Sat Stargaze 7:00 pm 10:00 pm Sat 15 Mar 2025 3rd Sat Stargaze 7:00 pm 10:00 pm Sat 05 Apr 2025 1st Sat Stargaze 8:00 pm 11:00 pm Sat 19 Apr 2025 3rd Sat Stargaze 8:00 pm 11:00 pm Sat 03 May 2025 1st Sat Stargaze 8:00 pm 11:00 pm Sat 17 May 2025 3rd Sat Stargaze 8:00 pm 11:00 pm Sat 07 Jun 2025 1st Sat Stargaze 8:00 pm 11:00 pm Sat 21 Jun 2025 3rd Sat Stargaze 8:00 pm 11:00 pm TAOCalendar Public Stargaze Jan-Jun 2025 These 2025 TAO Public Stargaze events are scheduled for fixed calendar days during the weekend, which will hopefully prove convenient for many visitors with families, especially those bringing younger astronomers. Cancellations often take place in Winter and Spring, due to cold or icy conditions, or overcast and rainy skies. www.roanestate.edu/obs www.ORIONinc.org v. 07 Jun 2025 cancelled cancelled cancelled cancelled cancelled cancelled cancelled cancelled cancelled date event details start end Sat 05 Jul 2025 1st Sat Stargaze 8:30 pm 11:30 pm Sat 19 Jul 2025 3rd Sat Stargaze 8:30 pm 11:30 pm Sat 02 Aug 2025 1st Sat Stargaze 8:30 pm 11:30 pm Sat 16 Aug 2025 3rd Sat Stargaze 8:30 pm 11:30 pm Sun 07 Sep 2025 “1st Sat” Stargaze 8:00 pm 11:00 pm Sat 20 Sep 2025 3rd Sat Stargaze 8:00 pm 11:00 pm Sat 04 Oct 2025 1st Sat Stargaze 7:30 pm 10:00 pm Sat 18 Oct 2025 3rd Sat Stargaze 7:30 pm 10:00 pm Sat 01 Nov 2025 1st Sat Stargaze 7:00 pm 10:00 pm Sat 15 Nov 2025 3rd Sat Stargaze 7:00 pm 10:00 pm Sat 06 Dec 2025 1st Sat Stargaze 6:30 pm 10:00 pm Sat 20 Dec 2025 3rd Sat Stargaze 6:30 pm 10:00 pm These 2025 TAO Public Stargaze events are scheduled for fixed calendar days during the weekend, which will hopefully prove convenient for many visitors with families, especially those bringing younger astronomers. Cancellations often take place in Winter, due to cold or icy conditions, or overcast and rainy skies. www.roanestate.edu/obs www.ORIONinc.org v. 24 Jun 2025 TAOCalendar Public Stargaze Jul-Dec 2025 cancelled cancelled moved www.roanestate.edu/obs www.ORIONinc.org v. 24 Jun 2025 (Trapezium) date event details start end Sat 04 Oct 2025 1st Sat Public Stargaze 7:30 pm 10:00 pm Mon 06 Oct 2025 Full Moon 11:47 pm Eastern Sat 18 Oct 2025 3rd Sat Public Stargaze 7:30 pm 10:00 pm Tue 21 Oct 2025 New Moon 08:25 am Eastern TAOCalendar Special Events Oct 2025 www.roanestate.edu/obs www.ORIONinc.org date event details start end Sat 01 Nov 2025 1st Sat Public Stargaze 7:00 pm 10:00 pm Wed 05 Nov 2025 Full Moon 08:19 am Eastern Sat 15 Nov 2025 3rd Sat Public Stargaze 7:00 pm 10:00 pm Thu 20 Nov 2025 New Moon 01:47 am Eastern TAOCalendar Special Events Nov 2025 Public Stargaze of Sat 20 Sep 2025 - Ted Barnes The surprisingly dark sky at TAO as of 8:19 pm Eastern, 20 Sep 2025. Sunset 7:39 pm Civ dusk 8:04 pm Ast dusk 9:05 pm Moonrise 6:10 am Moonset 7:09 pm Sat 20 Sep 2025 Moon illum. 2% Waning Crescent Moon. No Moon visible during this event. After some online discussion of the best date for this event it was finally decided that the predicted weather for Sat 20 Sep had better prospects than Sun 21 Sep, so it was announced that this Public Stargaze would be on Sat 20 Sep, as planned. TAO was scheduled to open at 8 pm. Due to some inefficient planning I managed to arrive at the TAO Gate much earlier, around 7:35 pm, and settled in for a wait. Two cars soon joined me in the admissions queue, and I had a déjà vu of waiting Two waiting to enter the Riverside Movie Theater in North Kansas City with my parents around 1960. It was already very dark as 8:00 pm approached, perhaps the opening time at this time of year should instead be 7:30 pm, so any first-time visitors would stand a chance in their first encounter with the TAO access road. On arrival at TAO I learned that my other car-bound waitees had been Art Allison and Don Spong, who soon began setting up their observing equipment. Due to general personal exhaustion and the stress of planning a future vacation, I had decided not to bring my telescope to this event. Instead I thought I would just bring my camp chair, give a short astronomy talk to our visitors, and then settle in to the lawn chair with binoculars. Both of these activities proved difficult; I had upgraded my recent occultations talk, but left that version on a home computer, and failed to copy it onto the memory stick I brought. I had hoped as a backup to store it on a TAO computer, but AD failed to connect, so that didn’t happen; no updated talk. No problem, David and Don gave talks. As for the binoculars, I had left them at home. So I admired the stars from a lawn chair without optical aid. We had 8 visitors, these being our two SMAS colleagues, four of Noah’s students and their friends, one with a charming little daughter, and Robert Corliss, who was very excited about a flyover by the Chinese Space Station. With myself, David Fields, Don Spong, Rob Fowler, Art Allison and Bob Edwards that makes 14. Or 15, once you include Sunny the Astrodog. A respectable group. 38 Public Stargaze of Sat 20 Sep 2025 (cont.) Don (foreground, with a surprisingly intense white light) and Art, setting up on the North and Northeast pads respectively. I had brought my “Meade kit” of useful items for the Meade LX-200, and after Rob started connecting things up I stopped by the glow dome to see if I could be of any assistance. Rob was just starting to align the system, so by pointing various lasers around and playing with the HC (antique hand controller) we managed to identify Nunki in the eyepiece. However all Rob really wanted was to show Saturn to our visitors, so we next simply pointed the OTA below the square of Pegasus and found it. Saturn presented a very pleasing image, the rings still being very narrow; one had the impression of a faint light cream colored disk with a spike through it. Our visitors all enjoyed it. 39 Public Stargaze of Sat 20 Sep 2025 (cont.) Above the glow dome one can easily distinguish Sagittarius (Sgr) and to the right, Scorpius, featuring Antares. And some whirls of cloud. Sgr Antares Nunki For our next public image, since Hercules was well placed high in the West, we decided to show our visitors the famous Messier-listed globular cluster M13. After checking where it was in the “keystone,” aided by my Celestron SkyPortal app, Rob was able to find it relatively easily as a small grey smudge. Improved focus turned this into a patch with visible stars. Since the visitors were still in the TAO lecture room we decided to attach a camera, one of my ZWO ASI294MCPs, and Rob captured several stacks of this beautiful object. As the lectures were just finishing I encouraged our visitors to come out and see our new astrophotos of M13. They were quite interested to see the comparison between the faint naked-eye object in the eyepiece and the very bright image captured shortly earlier as a stack, using SharpCap. One of the Meade-LX200 stacked images of M13 is shown below, after post processing. Public Stargaze of Sat 20 Sep 2025 (cont.) This image was taken using a ZWO ASI294MCP, and is a stack of 6 frames at a gain of 520, each frame just over 4 secs. The exposure midpoint time was 10:40:54 pm Eastern. 40 Due to other commitments, Bob Edwards and Art Allison both departed early, at about 10 pm. After some time spent chatting, I departed about midnight, leaving Rob, David and Don still at TAO. It is easier to leave when you have brought little equipment, so this was a relatively simple departure. Don had been working on images of the Veil Nebula; we can see some of his work from this evening in the Astrophotography section of the current (Oct 2025) issue. 41 Public Stargaze of Sat 20 Sep 2025 (cont.) Don Spong encourages the Moon to continue rising. Sietske and I decided to go out and sample the local skies. In Cloudcroft itself there were high, bright white streetlights, and you could only see black sky without stars between them. We decided that a drive beyond the village limits was appropriate. After some confusion we chose New Mexico State Rd. 130, which continued South from Cloudcroft, and descended into a dark National Forest with a few open areas along the sides of the road. Not expecting anything especially notable, we drove for about 10 miles, and around 8:40 pm I stopped at a pulloff that seemed to be set low between two steep cliffs. After I stopped the car Sietske climbed out of the passenger side, and I heard a soft exclamation. I climbed out the driver’s side and looked up, left, right, and various directions. The sky was intense. Yes, I could see the Milky Way near Cassiopeia to my right, but that band of greyish light was bright, and one could easily see complicated structures and star clouds comprising the band. It was too much. I looked away and saw Boötes and Corona Borealis, the latter a garish circlet of glowing white, cream and reddish coals. Up again, and you saw more of the Milky Way. With silence, and maybe a hint of wind. And something else, something weird and unexpected. It was very faint at first, and I thought I had imagined it, but when I listened very carefully, I could repeatedly hear a soft tinkle of music accompanying the stars. It seemed to drift in and out, a strange sci-fi kind of melody, with an even fainter, somewhat discordant background line. Was this really my imagination? Was someone in one of the sheds you could just make out in the darkness across the road, against the hillside, playing a little hint of music to celebrate the night sky? Might it even be another astronomer nearby with a little radio on for entertainment? I asked Sietske if she had heard the faint music. Yes, she said, she heard it, but it wasn’t music. What she heard was more of a faint, distant, screaming. And she was getting back in the car, now! I really didn’t need to hear that, I was enjoying the stars so much, but the “music” continued, strange and discordant and perhaps disoriented. I decided that inside the car was the better place to be, so I climbed back in and we drove back towards Cloudcroft. A Night in Cloudcroft (cont.) 48 49 A Night in Cloudcroft (cont.) Don Spong encourages the Moon to continue rising. Sietske said that was the most remarkable sky she had ever seen in her life, even as a hiker, with several years of experience with New Mexico. Perhaps because we were on a very dark road shielded by steep cliffs, and at an altitude of 8500 ft? She also said that she recognized the strange distant “music” that I had interpreted as other-worldly sci-fi / UFO type “Music from the Hearts of Space,” and she looked for an example of this faint cacophony on her cell phone. She had recognized it as the cry of a mountain lion. The locals know not to encounter mountain lions. I did manage to capture one cellphone image, to the Northwest, before getting back into the car. That image, enhanced, is at bottom left; some residual twilight is evident. Aldebaran is at image bottom left; image center is in Northern Boötes, at ca. RA 14.5h, Dec +50oN. The next morning we met our Real Estate Agent in Alamogordo, and with her assistance we did visit the potential New Mexico observatory property. The house was very beautiful. There were complications, such as being 200 miles from Albuquerque, having “just” Bortle 3 skies (the same as the previous night), and most of the surrounding 55 acres being on various extreme slopes. The most important complication was that someone else had recently made an offer, so the property was likely no longer available. The following day we managed to visit White Sands and the Very Large Array near Socorro, and learned that “Pie Town,” West of the VLA, also had potential observatory properties available, albeit under Bortle 1 skies. The search continues. 10:28 am, 26 Sep 2025. A potential observatory. 8:40 pm, 25 Sep 2025. 10 mi. S of Cloudcroft. The Stargazey Events of Thu 02 Oct 2025 - Ted Barnes Don Spong setting up on the North pad while Noah’s Roane State Astronomy class prepare a debate regarding the reality of the Apollo moon landings. 7:17 pm Eastern, 02 Oct 2025. Sunset 7:20 pm Civ dusk 7:45 pm Ast dusk 8:45 pm Moonrise 4:58 pm Moonset* 3:26 am * 03 Oct Thu 02 Oct 2025 Moon illum. 74% Waxing Gibbous Moon. Bright Moon visible during this event. Many things happened on this pleasant evening, so I will give a quick summary that will be somewhat unfair to all, especially since I don’t recall exactly how the organization took place. In online discussions using WhatsApp I think Noah Frere had mentioned that he would be going to TAO early on this evening, as early as 5 pm, since he would be teaching a class of astronomy students and needed some time to prepare. Coincidentally some of us had noticed that there was was an attractive possibility to observe an occultation that evening, involving the outer main belt asteroid 1298 Nocturna and an unusually bright star of g-magnitude 10.4 in the constellation Sagittarius. Of course this time of year observing anything in Sagittarius would be an early evening event, and the occultation would accordingly be an early one, at 8:33 pm. One would have to arrive and set up early, but this could mesh with Noah’s plan to open TAO early, in the late afternoon. I expressed interest online, as did Rob Fowler and Art Allison. Don Spong also stated that he might arrive to take advantage of the opportunity for astrophotography. So, we had spontaneously organized an astronomy evening with at least five additional astronomers and Noah’s group of students. Alles gut! Stargazey Events of Thu 02 Oct 2025 (cont.) My occultation setup, largely complete, still lacking some cables and the monitor. Note my new safety device, a black net bag to capture the gps camera should its holding screws fail. 7:05 pm Eastern, 02 Oct 2025. Noah said that he would be using the Meade LX-200 with the students, so I brought along my Meade kit to help out. Since Rob was accordingly available to help me with capturing this early occultation, he rode with me for convenience, and planned to share a ride back relatively early. On arrival soon after 6 pm we began assembling my usual setup, and had everything ready to start realignment around 7:25 pm. (See image below.) A move requires a change of site location coordinates in CPWI, and usually a new alignment. In principle one can just load an old set of alignment stars and resync, but that shortcut is typically problematic. Turning CPWI and PHD2 on, I loaded an earlier TAO alignment set, and a slew to Kochab showed it nearly centered in the guide scope. I turned on SharpCap and centered Kochab and then Thuban, most promising, but I when tried a slew to nearby Alkaid it wasn’t even in the guidescope’s field. Also on the negative side, the laser was alternately weak or out, and SharpCap’s plate solve tool failed to solve. About 8:00 pm Noah sent his rather large class over to our Northeast pad for a quick chat about our occultation plans. I handed out some hand-drawn occultation local field star charts I had prepared to Don and Noah, who had said they too might try to capture the occultation. Stargazey Events of Thu 02 Oct 2025 (cont.) Art near the glow dome, capturing deep-sky images with his Seestar S50. Rob and I finished our discussion with the students around 8:11 pm, which left us with only about 20 minutes to align the telescope, find the target star, and prepare to capture the occultation. Well that was the problem of course, this was an EARLY event, and success would require that nothing go wrong. And here I was still muddling with finding Alkaid, far from Sagittarius. So I dropped that and tried a slew to Aldebaran, halfway to Sgr. It appeared in the guidescope! It was alas also in the one TAO tree, drat, and the OTA couldn’t see it clearly. So I added it as best I could, and slewed to Sabik, h Oph. Nothing appeared. I kept trying to use SharpCap’s plate solver tool, but it repeatedly failed to function. Rob told me I had about five minutes remaining until the 8:33 pm occultation. I tried a slew to Kaus Borealis, the lynchpin in the Sgr teapot, and a star appeared. No time to check anything. I added it to the alignment stars and did a final “Hail Mary” slew to the nominal coordinates of the target star, TYC 6859-00173-1, in NE Sgr. God knows where the OTA was actually pointing by then. Oh well, it’s all good practice. The field didn’t look much like my star chart, but this was the best I could do. Noah yelled from the glow dome that he would send his students over to watch the occultation, but I yelled back that we don’t have it (the target star). Art volunteered to entertain the students. I set SharpCap to capture a 1000-exposure SER movie of 200ms frames at the maximum QHY174MGPS camera gain of 480, and at about 8:33:00 pm I began capturing frames. That was it. Nothing more I could do. Stargazey Events of Thu 02 Oct 2025 (cont.) Not long after the event, Don strolled by and told us he thought he had captured the occultation. He showed us some images on his tablet, with the star being “out” in at least two. I didn’t understand this since he said they were 200ms frames, but ok, if the star went out, he must have captured it! Good for him, but personally I was feeling demoralized. Things I was most unhappy about included 1) my green laser pointer, which kept going out whenever it was most needed, 2) SharpCap’s failure to plate solve, which I REALLY needed, 3) my inability to align this system at a remote location with CPWI and keep it aligned in future with the same stored set of alignment stars, 4) my PHD2 OTA guiding system, which really needs to be recalibrated, but according to the popup instructions that should only be done when the guidescope is pointed towards a suitable location in the sky, whatever that might be. This list could go on. Anyway, after the event, with the time pressure off, I went back to adding more stars in Sgr to my set of alignment stars, repeatedly telling the system to slew to the known coordinates of the target star. Strangely, it kept going to almost the same location it had used before; I recognized that field by now. Might I have accidentally captured the event, despite the chaos of the last few minutes before the dreaded 8:33 pm? When I compared the chart I drew from The Sky X (rotated by p) with an image I had captured of what might be the target star’s field, after some comparison I could see that the two fields really did coincide! (See next page.) Thus there was a good chance that the SER movie really did capture the occultation! One of the puzzles that had thrown me in trying to identify the target star by comparing my chart (hand-drawn from The Sky X) to my camera images is evident on the next page. The Sky X shows a moderately bright star of magnitude 12.2, labelled GSC 6859:772, just below the target star. My captured image shows no such star. The Gaia database in Aladin v.12 shows a star at this location, Gaia EDR3 4078656701299780480, but it is much fainter, with a g-mag of only 15.4. Perhaps this is a long-term variable, or just a misidentified asteroid? In any case this apparent mistake in the chart (following page, top) is one reason I was unsure about whether we had actually found the correct target star, TYC 6859-00173-1. 53 Stargazey Events of Thu 02 Oct 2025 (cont.) Showing that the target star chart (top) and my telescope image (bottom) do coincide! target star TYC 6859-00173-1 Chart: The Sky X (rot by p) spurious “star” in the chart? Stargazey Events of Thu 02 Oct 2025 (cont.) Once it appeared likely that we really HAD captured the target star in our original SER movie of 8:33-35 pm, which had become evident about 10 pm, I felt brave enough to suggest to Rob that we actually watch the movie. Normally I prefer to take the images home and carefully identify each important field; jumping to the relevant SER movie file immediately at TAO seemed like tempting fate. However Rob was all for it, and since I had suggested it, we pretty much had no choice, if I was to avoid looking like a chicken. So, I loaded the 1000-exposure SER movie into the SER player and hit start. The first (gps-timed) exposure started at 08:33:01.315 pm Eastern, and the frames advanced in 200ms steps. The target star was surprisingly bright. When we reached about 08:33:36 pm THE STAR WENT OUT. It stayed out until about 08:33:39 pm. WE HAD CAPTURED THE OCCULTATION! I let out a number of undignified “yes!” noises, so much so that Art yelled over to ask if I was ok. Yes, Yes and Yes! We had captured the occultation by 1298 Nocturna after all! At home on 3 Oct I used Pymovie and PyOTE to analyze the event in detail. With 1s error bars, the PyOTE square well fit has identified Disappearance and Reappearance times (Eastern) of D = 08:33:36.484(8) pm and R = 08:33:39.063(8) pm, giving a duration of 2.58(1) secs. These observations are consistent with predictions, but have much smaller errors, of about a hundredth of a second. The fit cites a magnitude drop of 5.2 +/- 0.7, also consistent with expectations. A plot of my fitted occultation data is shown below. Here the upper (purple) points are from a comparison star, the middle (dark blue) points that show the occultation are from the target star, and the pale blue points at bottom are from an empty “no star” aperture of the same size, as an indication of the background count level. What is especially interesting is that Richard Piety also captured this event at his home observatory RPO in Powell, which is a considerable distance from TAO. This will allow some interesting future comparisons. 55 Stargazey Events of Thu 02 Oct 2025 (cont.) The basic information extracted in a simple occultation are the target star’s disappearance time D, reappearance time R, and the duration of the event, which is the difference R-D. In Richard’s case the values determined by pymovie and pyote at 1s significance are as follows: D = UT 00:33:39.3537(39) R = UT 00:33:42.0200(39) Dur = R-D = 2.6663(54) secs. In comparison at TAO I had D = UT 00:33:36.4835(85) R = UT 00:33:39.0633(85) Dur = R-D = 2.5798(121) secs. The difference in durations, DDur = 0.087(13) secs is statistically significant, and is an observation that the shadow of the asteroid, and hence the duration of the occultation, is longer near the shadow midline. TAO was 8.5 km from the centerline, whereas Richard’s RPO was 6.1 km from the centerline. Given an estimated diameter of 40 km, and a predicted max dur of 2.5 secs, if we assume a circular shadow, the duration at RPO should be longer than the duration at TAO by 0.12 secs, comparable to what was observed. This is a first step towards measuring an asteroid’s profile. Similarly, the disappearance at RPO was predicted to be about 3 secs later than at TAO, and the actual difference was DD = 2.87(9) secs. From the known shadow velocity we can infer that Richard’s site RPO is roughly 43 km from TAO. An actual comparison of these distances will be followed up in the next issue. 56 Public Stargaze of 04 Oct 2025 - Ted Barnes The view to the West, 7:47 pm Eastern, 02 Oct 2025. Sunset 7:18 pm Civ dusk 7:44 pm Ast dusk 8:43 pm Moonrise 5:58 pm Moonset* 5:46 am * 05 Oct Sat 04 Oct 2025 Moon illum. 91% Waxing Gibbous Moon. Nearly Full Moon during this event. Although the weather predictions suggested that the skies for this Sat night would not be the best, and Sun might be somewhat better, David decided to proceed as usual, and urged the usual astronomy types to arrive by 8:00 pm. I actually arrived somewhat earlier, about 7:30 pm, without equipment (I was still recovering from the 02 Oct occultation), but with Meade box in tow to help with visitors. Initially I only encountered Rob, but soon David appeared, as did Noah’s student Paige and friend Aaron. as and friend Aaron. Art and Don also appeared, with Janet Spong, as did Bob Edwards and Robert Corliss, so we had an ample supply of astronomers as well as interesting characters. Gradually the number of visitors increased, until we had something like ten.hearing their stories Titan and shadow transiting Saturn - John Cliff Despite questionable weather predictions, Noah Frere and John Cliff decided to set up for planetary imaging of Titan's eclipse of Saturn at John's home on September 19, as it was the last chance to catch such an alignment until the year 2040. The pair were rewarded for their persistence as the clouds started to clear at around 02:45 on the 20th. Despite marginal transparency, Cliff was able to capture the last part of the eclipse using the technique of lucky imaging. Out of about 15,000 25ms frames acquired for each broadband filter (red, green, and blue), the best 15% were chosen, stacked, derotated, and sharpened using freely available software. Titan is visible below and left of its shadow on Saturn's outermost cloud bands in the processed image. The technique of lucky imaging for planetary and lunar astrophotography will be covered in a future ORION seminar. Veil Nebulae - Don Spong This month I’ve worked on imaging the Veil Nebulae in the constellation Cygnus. Cygnus is in a good position directly overhead from August through early October. I had imaged these nebulas earlier, but wanted to revisit them with my new camera. The following two images are parts of a larger loop structure in Cygnus and ideally, if time were available, it would be nice to assemble mosaics that would put all of these parts into one integrated image. However, I haven’t had time to do that. These nebulae were created by the explosion of a star about 20 times more massive than our sun, 10,000 to 20,000 years ago. The image below is the Western Veil Nebula, and the following is the Eastern Veil Nebula. These were taken on September 20 and 29 using my Celestron Edge HD, ZWO AM5 mount, Hyperstar attachment, ZWO 2600 MCPro camera, Williams Optics guide scope, ZWO 220MM guide camera, Antlia triband filter, all controlled by my ZWO ASIAIR. Around sixty 60-second images were stacked to form these images. The Western Veil Nebula Veil Nebulae (cont.) The Eastern Veil Nebula 67 Appendices Astronumerology - tb Some numbers are quoted to several-digit accuracy where appropriate. Exact numerical relationships are indicated as such. 1 ly = 1 ly (Julian) = exactly 9 460 730 472 580. 8 km = 63 241. 077 084 … AU c = speed of light = exactly 299 792 458 m/s = exactly  1 ly/yr. 1 AU = exactly 149 597 870. 7 km 1 parsec (pc) = 3. 261 598 … light years (ly) 1 yr (Julian) = exactly 365.25 d = exactly 31 557 600 s 1 d = exactly 86 400 s distance to a Cen A = 1.346(2) pc = 4.390(8) ly distance to the center of the galaxy ~ 8 kpc ~ 25 kly (considerable uncertainty) 1 nm = 1 nanometer = 10-9 m exactly Ha wavelength = 656.2 nm + 0.5 change in magnitude = exactly 101/5 x fainter = 1. 584 893 … x fainter + 1 change in magnitude = exactly 102/5 x fainter = 2. 511 886 … x fainter + 2 change in magnitude = exactly 104/5 x fainter = 6. 309 … x fainter + 2.5 change in mag = exactly 101 x fainter = 10 x fainter + 3 change in mag = exactly 106/5 x fainter = 15. 848 … x fainter + 4 change in mag = exactly 108/5 x fainter = 39. 810 … x fainter + 5 change in mag = exactly 102 x fainter = 100 x fainter + 6 change in mag = exactly 1012/5x fainter = 251. 188 … x fainter + 7.5 change in mag = exactly 103 x fainter = 1000 x fainter + 8 change in mag = exactly 1016/5 x fainter = 1584. 893 … x fainter + 10 change in mag = exactly 104 x fainter = 10 000 x fainter + 20 change in mag = exactly 108 x fainter = 100 000 000 x fainter Brightness is proportional to 1 / distance2 10 x more distant = exactly 102 x fainter = + 5 change in magnitude 102 x more distant = exactly 104 x fainter = + 10 change in mag 103 x more distant = exactly 106 x fainter = + 15 change in mag Absolute magnitude Mabs is the brightness as seen from a distance of 10 pc. Mabs (our sun) = 4.83 17th mag is about 1 optical photon / cm2 s ( Barnes’s rule  ). 68 Astronumerology (cont.) Some numbers are quoted to several-digit accuracy where appropriate. Exact numerical relationships are indicated as such. R.A. = RA = Right Ascension = the angle f around the celestial polar axis, usually quoted in hours, minutes, and seconds (h m s); analogous to longitude. Dec = Declination = the angle q above the celestial equator, usually quoted in degrees, minutes, and seconds ( ° ' " ); analogous to latitude. The RA (f) and Dec (q) angles, together with a reference epoch such as J2000.0, specify an object’s direction in the sky. A unit length vector (“unit vector”) h pointing towards an object in the sky (“on the celestial sphere”) in terms of RA (f) and Dec (q) angles is given by h = cos(q) cos(f) x + cos(q) sin(f) y + sin(q) z = C (c x + s y) + S z The arc angle Q12 between any two directions in the sky h1 and h2 (or any two stars) using the dot product formula and some obvious abbreviations, satisfies cos(Q12) = sin(q1)sin(q2) + cos(q1)cos(q2)cos(f1-f2) = S1S2 + C1C2c1-2 1 degree = p/180 radians = 1.745 10-2 radians 1 arcmin = p/10800 radians = 2.909 10-4 radians 1 arcsec = 1 asec = p/648000 radians = 4.848 10-6 radians 1 mas = 10-3 asec = 4.848 10-9 radians 1 asec @ 1 km = 4.848 mm 1 asec @ 1 AU = 725.3 km 1 asec @ 1 pc = 1.0000 AU 1 mas @ 1 kpc = 1.0000 AU Image scale [asec/px] = 206.3 * pixel size[mm] / focal length [mm] JD = Julian Date (Astronomer’s calendar) = a simple count of days starting at noon UT on Monday 1 Jan 4713 BC. That date and time was the start of Julian Day 0. The current JD can be inferred from the value on the cover of the Trapezium. 69 1 Sirius 02 Canopus 03 alpha Centauri A 04 Arcturus 05 Vega 06 Capella 07 Rigel 08 Procyon 09 Archenar 10 Betelgeuse 11 beta Centauri 12 Altair 13 alpha Crucis 14 Aldebaran 15 Antares 16 Spica 17 Pollux 18 Fomalhaut 19 Deneb 20 Mimosa 21 Regulus 22 Adhara 23 Castor 24 Shaula 25 Gacrux 26 Bellatrix 27 Elnath 28 Miaplacidus 29 Alnilam 30 Regor 31 Alnair 32 Alnitak 33 Alioth 34 Dubhe 35 Mirfak 36 Wezen 37 Sargas 38 Kaus Australis 39 Avior 40 Alkaid 8.709 0.0054 309. 16. 4.395 0.0083 36.72 0.22 25.04 0.069 42.81 0.26 863. 78. 11.46 0.051 139.4 3.4 498. 63. 392. 24. 16.73 0.049 322. 16. 66.64 1.05 554. 94. 250. 13. 33.78 0.09 25.13 0.09 1410 200 279. 23. 79.30 0.67 405. 7.0 50.68 0.032 571.2 7.5 88.56 0.43 252.4 10.2 133.9 1.9 113.2 0.43 1980 540 1120 110 101.0 0.66 736. 106. 82.55 0.42 122.9 2.2 506. 13. 1610 300 300. 41. 143.3 1.5 605. 47. 103.9 0.79 41 Menkalinan 42 Atria 43 Alhena 44 Peacock 45 Alsephina 46 Mirzam 47 Polaris 48 Alphard 49 Hamal 50 Diphda 51 Mizar 52 Nunki 53 Menkent 54 Alpheratz 55 Mirach 56 Rasalhague 57 Algieba 58 Kochab 59 Saiph 60 Denebola 61 Algol 62 Tiaki 63 Muhlifain 64 Aspidiske 65 Suhail 66 Alphecca 67 Mintaka 68 Sadr 69 Eltanin 70 Schedar 71 Naos 72 Almach 73 Caph 74 Izar 75 alpha Lupi 76 epsilon Centauri 77 Dschubba 78 Larawag 79 eta Centauri 80 Merak 81.1 0.46 390.6 7.0 109.3 8.2 178.8 5.1 80.6 0.78 492.7 16.4 432.6 6.3 180.3 1.8 65.8 0.33 96.3 0.46 81.1 0.93 227.8 4.6 58.8 0.21 97.0 1.01 197.4 6.7 48.6 0.77 130.1 2.7 130.9 0.63 974. 37. 35.9 0.21 89.9 3.47 177.0 4.0 130.2 1.5 765.6 18.0 544.5 10.0 77.2 1.79 692.5 85. 1830 270 154.3 0.7 231.5 8.2 1080 40 393.0 49. 54.7 0.35 235.9 8.4 464.6 11. 427.5 27. 491.2 66. 63.7 0.27 305.7 6.0 84.5 2.5 The 80 brightest stars (c/o Wikipedia), and their distances from Earth in light years, with errors (from Gaia data, or Simbad if needed as an alternative). The 80 Brightest Stars 71 Schedar Caph 5 -0.085 1.7 Betelgeuse Alnitak 10 0.017 0.17 Capella Castor 30 -0.023 0.077 Procyon Mirzam 30 -0.094 0.31 Elnath Alnilam 30 -0.096 0.32 Alpheratz Caph 30 0.060 0.20 Aldebaran Pollux 45 0.013 0.029 Betelgeuse Algol 50 -0.033 0.066 Alnitak Naos 50 -0.049 0.098 Pollux Alioth 60 0.065 0.11 Gacrux Alphard 60 -0.001 0.002 Regulus Bellatrix 70 -0.030 0.043 Sirius Mirfak 80 -0.094 0.12 alpha_Centauri Regulus 90 0.057 0.063 Vega Denebola 90 -0.065 0.072 Fomalhaut Caph 90 0.006 0.007 Deneb Alnilam 120 0.059 0.049 Menkent Mintaka 120 0.000 0.000 Sirius Alphecca 135 -0.089 0.066 Aldebaran Antares 170 -0.021 0.012 Notable star pairs (from the set of the 80 brightest stars listed above) that are close to a multiple of 5o separation. The angles are in degrees. Notable Star-Pair Angles Q Dq defect (%) 72 Exeunt Poetica Contributed by the Editor. What the British had to say about their geography during the Dark Ages: The Land of Britain The island of Britain lies virtually at the end of the world, towards the west and north-west. Poised in the divine scales that (we are told) weigh the whole Earth, it stretches from the south-west towards the northern pole. It has a length of eight hundred miles, a width of two hundred: leaving out of account the various large headlands that jut out between the curving ocean bays. It is fortified on all sides by a vast and more or less uncrossable ring of sea, apart from the straits on the south where one can cross to Belgic Gaul; but it has the benefit of estuaries of a number of streams, and especially two splendid rivers, the Thames and the Severn, arms of the sea along which luxuries from overseas used to be brought by ship. It is ornamented with twenty-eight cities and a number of castles, and well equipped with fortifications - walls, castellated towers, gates and houses, whose sturdily built roofs reared menacingly skyward. Like a chosen bride arrayed in a variety of jewellery, the island is decorated with wide plains and agreeably set hills, excellent for vigorous agriculture, and mountains especially suited to varying the pasture for animals. Flowers of varying hues underfoot make them a delightful picture. To water it, the island has clear fountains, whose constant flow drives before it pebbles white as snow, and brilliant rivers that glide with gentle murmur, guaranteeing sweet sleep for those who lie on their banks, and lakes flowing over with a cold rush of living water. Gildas, “De Excidio Britonum” ca. 540 A.D.