Mobile and Remote (pre-pointing) and Long Distance Asteroidal Occultation Observation

1. Mobile and Remote (pre-pointing) and Long Distance Asteroidal Occultation Observation 2018 April 20 David W. Dunham

2. Better Visual Timing with Shortwave Radio (for WWV)and cassette audio tape recorder (now can use cell phone video, just for the audio recording)

3. Remote Stations for Asteroidal Occultations • Separation should be many km, much larger than for grazes, so tracking times & errors are too large • Unguided is possible since the prediction times are accurate enough, to less that 1 min. = ¼ • Point telescope beforehand to same alt. & az. (or hour angle & dec.) that the target star will have at event time and keep it fixed in that direction • Use the list of prepoint stars on Derek Breit’s Web site; I use a DOS computer program that reads that file to calculate U.T.’s of prepoint stars, as the new Occult will • I used to use the Millennium Star Atlas (ok when the epoch was close to 2000), but now I use Guide8 to generate the pre-point charts with the pre-point line of declination. C2A also generates them. I make star charts of all possible opportunities after it becomes dark enough to see Polaris by naked eye • From the RA difference and event time for the area of observation, calculate times along the declination line • Adjust the above for sidereal rate that is faster than solar rate, add 10 seconds for each hour before the event [Occult 4, Guide8, & C2A make the adjustments] • Can usually find “guide stars” that are easier to find than the target • Find a safe but accessible place for both the attended & remote scopes • Separation distance used to be limited by travel time & tape to start tapes • Roger Venable uses VCR’s with timed starts, allows larger separation • Sometimes have remote sites attended for starting equipment later (allows larger separations) and security

4. Example 1 of Guide8 Pre-Point Chart

5. Example 2 of Guide8 Pre-Point Chart

6. Other uses for pre-pointing • So far, pre-pointing has been used mainly for remote stations, but there are other reasons to do it • Since stars much brighter and easier to find than the target can be used, it can help you lock on the target star at the right time and avoid the common failure of not doing that in time • You could prepoint one or more telescopes of other observers in your area early in the evening to get additional chords around your city • Helping other observers in this way might shame them into learning the sky and doing the job themselves, valuable for later events when they could make an independent observation

7. Occultation of the 6.0-mag. Close Double Star SAO 78349 by (9) Metis on 2001 September 7 • The star was known to be a close double, sep. about 0.08” with 6.5 and 6.9-mag. Components, from a photoelectric lunar occultation recording at McDonald Obs., Texas, on 1973 April 9 • Best asteroidal occultation of 2001 in the U.S.A. • Unfortunately, 1 night before the occultation of a 7th-mag. Star by Uranus’ satellite Titania in Europe & n. S. America • I made the first REMOTE recording of an asteroidal occultation during this event, in the Sacramento Valley of northern California

8. Sky-plane plot of Metis occ’nfrom March 2002 S&T

9. Remote equipment at Orland, CA

10. Another viewThis used my image intensifier and a 50mm Nikon lens, but similar results (with a narrower, about 3°, field of view) are possible with the PC164C.

11. Successful Remote + Attended Positive Observations from 2 or more stations • 2001 Sept. 7, 9 Metis, northern California, D. Dunham • 2002 April 21, Oriola, Washington, S. Preston • 2003 Jan. 17, Bathilde, Georgia, R. Venable • 2004 July 1, Nanon, s. Calif., D. Dunham, but D. Stockbauer was at “remote” site, turned on recorder without changing pointing • 2004 Oct. 6, Ute, North Carolina, D. Dunham • 2004 Oct. 29, Flora, New Mexico, D. Dunham • 2005 Mar. 12, Bathseba, Georgia, R. Venable • 2005 May 13, Dufour, NSW, AU, D. Gault (home “remote” & mobile) • 2005 Dec. 1, Laurentia, Georgia, R. Venable • 2005 Dec. 1, Dike, Maryland & Virginia, D. Dunham (3 observations, Joan Dunham helped) • 2005 Dec. 3, Europa, California, D. Dunham • 2006 Jan. 28, Veritas, North Carolina, D. Dunham • 2006 Feb. 24, Turandot, Indiana, D. Dunham (3 observations, Chuck Bueter helped) • 2006 June 12, Pallas, Georgia, R. Venable (4 observations!) • 2007 Jan. 10, Nysa, Georgia, R. Venable • 2007 Feb. 21, Thisbe, Florida, D. Dunham • 2007 Feb. 28, Nemausa, California, D. Dunham • 2007 Apr. 13, Fortuna, Virginia and N. Carolina, D. Dunham • 2007 Apr. 22, Dike, Florida, R. Venable (1st asteroid in this list twice) • 2007 May 24, Papagena, Maryland and Pennsylvania, D. Dunham (3 observations) • 2007 July 10, Nausikaa, R. Venable, Georgia • Several other cases where 2 stations were run and 1 had an occ’n & the other a miss, especially by Roger Venable; example was my observation of Rhodope occulting Regulus on October 19

12. Please do not disturb - Precisely Pointed Automatic Astronomical Station to Record the eclipse of the star TYC 0483-01460-1 by the asteroid 491 Carina at 4:28 am PDT this morning If you have any questions or concerns, call my cell phone, 301-526-5590, I’m nearby David Dunham, International Occultation Timing Assoc.

18. The video files are In c:\avi\mp99*.avi

19. Travel by air plane • Paul Maley, Richard Nugent, and I do this often for asteroidal occultations • More events accessible • Check for events in nice places, plan your vacation around them, combine with visits to relatives, etc. • Check your schedule & the Web sites for good events that might be observed during business and other trips you need to make for other reasons • Carryon systems, Meade 4” ETX & image intensifier to record 12th-mag. stars

20. Telescopes in checked luggage • 50-lb limit for all US domestic & many international flights requires compact, light-weight equipment • For bright events, use 50mm lens & PC164C or WAT cameras on small tripods • For telescopes, use small mounts, like stick mounts for 4” ETX, Tuthill mount for C5 & C8, Tabletop mount (disassemble & put screws, washers, & Allen wrench in plastic bag taped to it) • Remove all screws that attach finder scope to main scope, put in small baggie, put that in the opening of the finder holder for the finder scope, and put the holder in a large ziplock baggie • Fill travel case with plastic foam, towels, and/or pillows to fill all space & protect the equipment • Towels needed to put on ground to lay on so you can polar-align the scope (approximately), to protect video equipment from dust and/or cold, small one to elevate time inserter GPS receiver, etc. • Wrap sealed batteries in towels and put in bottom of case to hide; airlines sometimes ask (rarely; only once for me so far) to open case & they don’t like sealed batteries • Write explanation for TSA, a sample is on next page, which I also put in my carryon bag that has all the video equipment; they appreciate the documentation & purpose • Expect some damage maybe 1 time in 10; I’ve never had a telescope destroyed • Damage is more likely when baggage handlers are rushed; check in your luggage at least an hour before the scheduled departure and try to select direct or through (no plane change) flights; if you need a plane change, try to select one with the wait at the change airport of at least 1.5 hours in case of delay of your 1st flight • For taking 2 or more scopes, I prefer Southwest, the only airline that allows 3 free bags • I demonstrated the Tuthill mount and some of these packing tips at the IOTA meeting

22. For More Information about IOTA and observing occultations: • http://iota.jhuapl.edu - my web site. • Updates by e-mail – dunham@starpower.net • http://www.occultations.org – the main IOTA web site • http://www.asteroidoccultations.com - asteroidal occultation updates • http://www.poyntsource.com/New/Global.htm - Derek Breit’s site, Maps of N. America, Europe, S. America, & Australia showing Preston’s paths, Googlemaps, station & prepoint lists, etc. • For interactive station planning, OccultWatcher by Hristo Pavlov (see his presentation) • http://www.asteroidoccultation.com/observations/Results - Brad Timerson’s report forms and North American results Web page