2012-06-14 Pluto occultation
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Overview
new rank old rank star occultation date RA J2000 Dec J2000 R I J K -------- -------- --------- ------------------- ------------- ------------- ----- ----- ----- ----- A2 3 P20120614 2012/06/14 03:25:22 18 35 48.6931 -19 17 43.617 13.60 11.69 10.14 8.88
ALERT: Possible Pluto occultation Wednesday night (2012/06/14 03:28 UT) from US East coast.
CONTACT: Leslie Young (layoung@boulder.swri.edu; work: 303-546-6057; home: 303-747-9161; skype: drpluto). Also see our planning pages in progress at http://wiki.boulder.swri.edu/mediawiki/index.php/2012-06-14_Pluto_occultation
ALSO SEE:
- http://occult.mit.edu/research/occultations/Pluto/P20120614/
- http://www.lesia.obspm.fr/perso/braga-ribas/campaigns/#June
SCIENCE MOTIVATION: Pluto's thin, nitrogen atmosphere is in vapor-pressure equilibrium with the surface ice, and changes seasonally. We've seen it double since 1988, and now we measure its pressure once or twice a year. The technique we use is stellar occultation, when a star passes behind Pluto's atmosphere. The atmosphere defocuses the starlight. By the timing of the fading of the star, we measure the pressure and temperature in Pluto's atmosphere at ~10 km resolution.
DETAILS OF TIMING: Topocentric predictions for the midtime depend on the combination of Pluto and star positions used, and vary by about 50 seconds for any location. The midtime also depends on the location, affecting the midtime by about 1 minute over the portion of the US East coast that can observe the event. Adding pad for Pluto's extended atmosphere and the chance of systematic errors in the star's right ascension, the recommended time is an uninterrupted run no smaller than 03:20:00 to 03:37:00 UT.
DETAILS OF LOCATIONS OF OBSERVABILITY: Predictions vary. Pluto's shadow is predicted to be observable anywhere North of approximately South Carolina in all predictions, but any location on the entire east coast of North America has a good chance of being in the shadow. Parts of Europe and Africa are are also in the shadow path. Pluto only subtends 0.1 arcsec, so small errors in the star position and Pluto ephemeris can move the predicted shadow path. Predictions tend to be good to about 500 miles, barring systematic errors. Multiple chords are critical for reconstructing, after the fact, the geometry of Pluto's passage. A mix of central and more grazing chords are most useful for most tightly constraining the geometric solution.
Pluto is very low and rising (e.g., ~20.2 deg at Boston, Philadelphia, Baltimore). Observing farther west from the coast makes this even harder. You will need a clear view of the Eastern horizon. A modern telescope with accurate pointing may be invaluable.
NOTES ON EQUIPMENT: Observe with 1-second readout time if you can, and choose a readout mode (region of interest, binning) to keep readout time less than 0.25 seconds, preferably less than 0.05 seconds. Observe open, or in I band.
Accurate timing is VERY important. Our goal is 50 ms.
- Accurate GPS times are ideal if you can do that.
- Network Timing Protocol (NTP) can help if you don't have GPS times.
- For other timing ideas, you can call Leslie Young.
We have a few specialized occultation cameras and experienced occultation observers. We may ask some of you if we can bring our own camera to your site.
To do: add notes on field of view, refraction, comparison stars.
Contents |
Updates
2012-05-25
- Added this section
Sites
By state, roughly North to South
Google maps: http://maps.google.com/maps/ms?ie=UTF&msa=0&msid=205223237036510607015.0004c1e8f2658578ba668
Nova Scotia
- 0.40m (16-inch) Burke-Gaffney Observatory. http://www.smu.ca/academic/science/ap/bgo.html and http://www.astronomynovascotia.ca/ (club). 2012-06-07 Leslie contact. Won't work. Light pollution, low altitude
Dave Lane
- Halifax 14-in personal telescope of Dave Lane. Darker skies than Burke-Gaffney.
New Hampshire
- North Groton. 12", private telescope of Gary Walker (See Maria Mitchell). Has Princeton Instruments Pixis 512B.
Vermont
- Amateur groups: [| stellafane] - contacted 2012-06-07 Leslie
Message distributed to members. Two observatory mounted telescopes at stellafane don't have view.
- [VT astronomical society] - contacted 2012-06-07 Leslie. 2012-06-08 Paul Walker distributed to members, also to VTASTRONOMY@LIST.UVM.EDU.
- 17-inch. Northern Skies Observatory http://www.nkaf.org/observatory/instruments. [Contact] - contacted 2012-06-07 Leslie, Out of town.
Middlebury
- 24-inch St Johnbury? 2012-06-07 Leslie contacted John Briggs. http://www.middlebury.edu/academics/physics/facilities/obs. Briggs contacted Frank Winkler <winkler@middlebury.edu> and Jay Pasachoff. 2012-06-08 Leslie checked on Talia and Kate's availability, and offered to send a camera or timer.
- 2012-06-11
MA
- IOTA (7) Werner Schmidt Observatory : video + gps Bernie Young 21° @144° South Yarmouth, Massachusetts
- 2012-05-29 Conard "I have been working with an observatory in Cape Cod, they can observe with a 0.4 m and an STV camera (right now they don't have any Johnson filters)"
- 2012-06-07 Conard "Private school in the Boston area with a brand new 24-inch"
Mario Motta
- Confirmed interest, PHOT camera. Leslie travel
- 32.25 inch very flat field F6, can track well
- on a hill, no obstruction, I have a 0 degree horizon all around except due north, small area 20 degree
- instrumentation
- SBIG STL 1001E CCD, that has 2.2 sec download time
- 2012-06-07 Glouster, MA. 32.25-inch private (Dr. Motta)
- wunderground http://www.wunderground.com/cgi-bin/findweather/getForecast?query=zmw:01930.1.99999. Clear sky clock: http://cleardarksky.com/c/GlcstrMAkey.html?1
Warner Schmidt
- Confirmed
- South Yarmouth, MA
- IOTA member Bernie Young.
- 18"
- instrumentation : video + GPS
- http://www.ccas.ws/cape_cod_observatory.htm
Maria Mitchell / Loines Observatory
- Telescope confirmed, instrumentation = facility + PHOT astrotimer
- 59 Milk Street Ext. Nantucket, MA 02554. (508) 228-9273
- http://www.mmo.org/observatories/observatories.html.
- 24" equatorial mount. Can point to a few degrees above Eastern horizon.
- Contact: Gary Walker, Vladamir Strelnitski
- Facility instrumentation: Princeton Instruments Pixis 512B. [fact sheet ] with an [FLI Atlas zero-tilt adapter fcouser].
- Issues with pixis: (1) Can the mechanical shutter be disabled? Otherwise there's 8 ms of shutter open and close time. (2) Can the camera be triggered? (3) Can we write multiple images, or is the write time per image short enough?
- According to http://www.princetoninstruments.com/Uploads/Princeton/Documents/Datasheets/PIXIS/Princeton_Instruments_PIXIS_512_eXcelon_Rev_N1_10.11.11.pdf, there is a trigger in.
- Issues with PHOT camera: (1) Mounting.
- Logistics: visiting scientist apartment, or B&B run by a board member's wife.
- Overhead tests: First I choose full frame, 1 second exposures, and saved them normally using Maxim. Qualitatively, I got 1 exposure every 3 seconds. I then subframed to 256 x 256 and repeated, using my iphone as a stopwatch, and captured 20 frames in 40 seconds. I then subframed to 125 x 125 and repeated. Got 20 frames in about 30 seconds. This was all done in slow read mode. I expect better results in high speed readout, but did not try this. ... I do remember that my old Photometrics (prior to PI) camera, at a ccd school in Tucson, did have a demonstration of making that camera go fast. I think they probably disabled the shutter and maybe external sync. I don't remember the details. Photometrics became Princeton Instruments some time back. I suspect that the same feature may also be available in the Pixis 512B.
- Weather: wunderground http://www.wunderground.com/q/zmw:02554.1.99999. Clearsky clock: http://cleardarksky.com/c/NntktMAkey.html?1.
- To Do: add timing update.
NY
- 2012-05-29 Conard: Emailed Stoll Observatory at Alfred College (where I tried last year)--the event isn't high enough to clear their tree line unfortunately.
PA
Swarthmore
- Confirmed
- Swarthmore College near Philidelphia. 24-inch. Does asteroid work. http://www.swarthmore.edu/academics/physics-and-astronomy/peter-van-de-kamp-observatory.xml. 2012-0607 Leslie sent email to physics@swarthmore.edu.
- Apogee U16M
- usually made with 2x2 binning, giving a binned pixel scale of 0.76" / pixel.
- Filters: Available filters are 50mm-square Johnson-Cousins UBVRcIc and SDSS u'g'r'i'z', both from Omega Optical. ... We also have a clear filter (which might be good for this) but I'm not sure if it's in the filter wheel at the moment.
- timing, we use Dimension 4 software (http://www.thinkman.com/dimension4/) for NTS.
Bruce Holenstein
- IOTA (6) Holenstein B Home : video + gps Bruce Holenstein 20° @139° Malvern, PA
- 12 or 14 inch SCT. Has the usual IOTA video+GPS setup. Also has some good cameras, could try the flash in the light path trick for timing.
Delaware
- Mt Cuba 24-in telescope http://www.physics.udel.edu/MCAO/about_mcao.htm. 2012-06-07 Leslie sent email to johninde@hotmail.com.
John Inde sent question to Greg.
Maryland
- Goddard. 2012-06-08 Leslie email Don and Dennis. 36 not operational, 48-inch is down.
- 2012-06-10 Don emailed cornelis.f.dutoit@nasa.gov re: astronomy club.
- UMCP 20-inch (0.5-m). Elizabeth Werner. Steve Conard contacted her, she sounded very interested. May have occultation instrumentation. http://www.astro.umd.edu/openhouse/3about-the-obs/telescopes.html. Should check with Mike A'Herne since he might have good instrumentation.
- Johns Hopkins Homewood campus. 0.5-m. But downtown Baltimore - too bright.
2012-05-29 Steve "I've sent email to the U of MD observatory, asking them to observe with their 0.4 m, still haven't heard back, I'll ping them again"
2012-05-29 IOTA list from Steve
-9514.0 km @194° 49.8% - (11) Conard JHU-APL : other + other Steve Conard 20° @137° Gamber, MD -9524.3 km @194° 49.8% - (4) Scaggsville, MD : video + gps Andrew Scheck 20° @137° Scaggsville, MD -9539.8 km @194° 49.7% - (8) Menke J Home : video + gps John Menke 19° @137° Barnesville, MD
UMBC
- UMBC 0.8 m http://jca.umbc.edu/telescope/astroclub.php. Greg Aring (aring1@umbc.edu).76O 42' 34.3" W Lat: 39O 15' 16.3" N.
focal length is 6.5m
Andrew Vache is checking if they have a 2-in eyepiece holder.
Cathy will bring PHOT camera to this site.
Scaggsville
- IOTA -9524.3 km @194° 49.8% - (4) Scaggsville, MD : video + gps Andrew Scheck 20° @137° Scaggsville, MD
- IOTA video + GPS
- 8-inch
- Worked with MIT group last year
Barnesville
-9539.8 km @194° 49.7% - (8) Menke J Home : video + gps John Menke 19° @137° Barnesville, MD
- 18-inch
John Menke
JHU-APL
- Confirmed
- 0.6-m on APL campus
- Good view of Eastern Horizon. May have dome pointing issues (in the middle of an upgrade).
- Contact: Claudia Knez
- Facility instrument - Atik camera, 640x480. Interline. 35-40% QE. Timing - Kiwi timer has flashing LED. => OK with facility instrument
Observatory/Observer City State Latitude Longitude Telescope Size (m) Camera Timing Contact Email Phone Notes JHU-APL Laurel MD 39 10 08.5 76 53 53.8 DFM R-C 0.60 TBD TBD Claudia Knez claudia.knez@jhuapl.edu Use arranged
2012-05-17 Steve Conard (Steven Conard <Steven.Conard@jhuapl.edu>) replied to Cathy
Cathy,
Ideally I’d like to use the “new” 0.6 meter here at APL, but I’m not sure I can make that happen (last I heard, they are still working on getting it fully operational). I’ll see if I can get some help from Hal and Andy Cheng on making that happen. Other options for me are the 0.5 meter at JHU Homewood, but that is has magnitude limit 2 skies in the center of Baltimore—I can use that for sure. There is also a 0.8 meter at UMBC near APL, but I’d be starting from scratch making contact with them. There are also possibilities at U of MD (0.4 m), Gettysburg College (0.4 m), and U of DE (0.4 m?).
BTW, I’ve found that schools with underutilized observatories are eager to work with us on our asteroid observations—for example I’m going down to Randolph College the weekend before to use their Winfree Observatory for an asteroid occultation, and I’ll be teaching several folks how to collect data for us on that trip. If we could supply cameras/filters, we might be able to set-up a network of ~0.5 meter scopes with an educational tie-in (time is likely way too short to organize it, though).
I have an ATIK camera with a small, fast reading array I can use. It can go at 1 Hz with low noise (<10 e) at 12 bits, or 3 to 4 Hz at 12 bits with about 4x more noise. I have V and I filters available, but you can always give me the excuse to buy another.
I can also contact the folks I worked with last year at Alfred University to see if they’d observe with their 0.8 m, plus there is another private school in the Boston area that has a 0.5 m and has done asteroids for us before. I’ll put out a call for the northeast IOTA folks, and see who else can help out.
2012-05-26 Leslie queried Hal Weaver, Andy Cheng re: APL. (Harold A Weaver <Hal.Weaver@jhuapl.edu>, Andy Cheng <Andy.Cheng@jhuapl.edu>)
DC
2012-05-26 Leslie queried Norbert Zacharias re: USNO. (Norbert Zacharias <nz@usno.navy.mil>)
Virginia
- GMU 0.8m 2012-06-08 Leslie sent email to Mike Summers
Fan Mt
confirmed
2012-05-26 Leslie queried Anne Verbiscer re: U. VA. (Anne Verbiscer <av4n@virginia.edu>)
2012-06-06 "The telescope is the 31" Tinsley Reflector on Fan Mt.: http://www.astro.virginia.edu/research/observatories/40inch/40-tools.php The coordinates from that page are -78° 41.6' East Longitude +37° 52.7' Latitude. ... The best contact would be Mike Skrutskie (mfs4n@virginia.edu) as he'll be doing the observing, weather permitting. The current forecast is not encouraging; however, we still are a week out, so perhaps it will change. Mike plans to postpone his departure to CO to do this, though if the forecast continues to be as bad as it is, he may leave as planned on the 13th. Since he's driving, he has much more flexibility than if he were flying. .. They are building the camera now, so the deadtime is unknown. Frame times should be known to 50ms.
Kentucky
Louisville
2012-06-05 Leslie check circumstances for Louiseville. Pluto rises about 10 deg at ~3:00 UT, or 25 minutes before event midtime.
2012-06-07 "Hi Leslie,...I checked tonight on the visibility of Pluto at the target time for June 14 using the Moon when it was very close to the same altitude and azimuth. It's a very close call. We have some trees to the south that may just block the view and I'll have to point the the telescope at the same HA and Dec to test this out because it's within a few degrees of go/no-go. ... We'll check this out more carefully and let you know tomorrow night if the weather allows. ... I have a mount for our camera and we could possibly get it on the CDK and working in time. However, I don't have GPS timing. We use NTP from a stratum 2 server for the exoplanet work with a jitter estimated at a few milliseconds. if that would serve."
2102-06-08 I pointed the CDK20 at the same altitude and azimuth as the Pluto event on the 14th. It looks like we have a sight line above the trees. The Moon tonight is so close that the field is bright. We should have clear nights this weekend and I'll take a few test frames to see what we can do at this low an altitude. ....The camera that's on the telescope now is an Apogee U16M with a Kodak KAF-16803 CCD. We also have a camera like yours with a similar CCD except its 1024x1024. The PCI card for it is missing (probably left in a PC that was moved). If we can't find it, then it would be a few weeks before we'd have a replacement. I should know sometime Friday or Monday.
2012-06-08: Emailed about potential suitability of facility camera and possibility of sending timing box (with email to Swarthmore).
NC
- 2015-06-07 Sicardy "It would be good to have a try fro Dark Sky Observatory, Appalachian, North Carolina,
http://wikimapia.org/17823/ (Daniel Caton): 80-cm, 45-cm, 42-cm, 35-cm" Contact is Dr. Daniel B. Caton, Ph.D. Professor and Director of Observatories Dept. of Physics and Astronomy Appalachian State University Boone, NC 28608. (828) 262-2446 (fax -2049) Mobile: (828) 964-6886. www.DanCaton.Physics.Appstate.edu catondb@appstate.edu
schedule at http://www.dancaton.physics.appstate.edu/Observatories/DSO/Facilities.htm
2012-06-08 Bruno contacted Dan.
2012-06008. too many trees that low at that azimuth
- Chapel Hill. 0.6m. http://www.physics.unc.edu/research/astro/observatories.php
- 3-college obs. status: no go elevation too low. 32-inch (0.8-m) Three College Observatory near Greensboro http://www.uncg.edu/phy/tco/tcotel.html.. Steve Danford contact. Jeff Regester to observe
Cline
- 16-inch
- Using PHOT/Ansel, Jeff observing.
Tenn
- To Do: contact Mark Manner has an observatory near Nashville with a 24-inch RCOS telescope and remote access to a CDK 24-inch nearby. If data from his latitude would be useful, you could contact him at Mark.Manner@h3gm.com . (John Kielkopf <jkielkopf@gmail.com> reference).
Georgia
- 16". http://www.valdosta.edu/phy/astro/opticaltel.shtml Martha Leake (Bob Howell connection). To do: email
- 20-in. http://www.chara.gsu.edu/HLCO/ Georgia State U, Atlanta. Harold McAllister (Bob Howell connection). To do: email
Trenton
- IOTA -13168.7 km @196° 41.0% - (10) Smith N Home : video + gps Ned Smith 18° @130° Trenton, GA
- 18 inch
Spain
- Liverpool Telescope in Canaries? TO DO: check status w. Marc.
Sant Esteve
- IOTA -13723.0 km @153° 39.6% - (3) Schnabel C Home : video + gps Carles Schnabel 21° @216° Sant Esteve Sesrovires
Cabrils
- IOTA -13821.9 km @153° 39.3% - (1) Naves R Home : drift scan + other Ramon Naves 21° @216° Cabrils
Astrometry and predictions
Positions
MIT 18:35:48.6883 0.002 –19:17:43.639 0.098 Paris/Brazil 18:35:48.6931 0.000 -19:17:43.617 0.000 Observational runs were carried out in Sep./Oct. 2007. Proper motions were applied
- MIT (using Assafin catalog) http://data.boulder.swri.edu/layoung/watchlist_20120327_frMJP/mjp_for_Leslie_120614.pdf and using SMARTS http://occult.mit.edu/research/occultations/Pluto/P20120614/index.html 18:35:48.6883 +/- 0.002 –19:17:43.639 +/- 0.098
- Bruno's latest: http://www.lesia.obspm.fr/perso/braga-ribas/campaigns/2012-06-14_03.432_Pluto.jpg 18:35:48.6931 -19:17:43.617. Also http://www.lesia.obspm.fr/perso/braga-ribas/campaigns/2012-06-14_Pluto.html.
- Assafin/no PM http://data.boulder.swri.edu/layoung/watchlist_20120403/20120614.pdf, Assafin stars, No proper motion applied, DE413, Bruno offsets to Pluto.
- Liverpool telescope http://data.boulder.swri.edu/layoung/watchlist_20120404_liverpool/0614.pdf, astrometry from Liverpool telescope in Canaries.
Liverpool telescope
Obsdate Star RA Dec Ns seeing FWHM occFWHM 111010 P120614 18:35:48.6900 -19:17:43.691 44 1.1 8.1 8.8 111010 P120614 18:35:48.6913 -19:17:43.690 44 1.0 7.5 7.9 * 111010 P120614 18:35:48.6877 -19:17:43.674 44 1.1 8.1 8.5 The first column is the observing date from LT. Then comes the occultation star name (short form). The next two columns are the J2000 measurements from a single frame (each one was imaged three times). Ns is the number of UCAC2 stars used (and kept) for the astrometric fit (strictly linear fit used). "seeing" is the FWHM in arcsec of the image measured from a random sampling of stars on the frame. FWHM is the same number just in pixels. The last column is the FWHM of the occultation star itself. I didn't average these down into final numbers as that involves other decision making (weighted/unweighted, etc.). I have put an asterisk on the line for the best image of the 3-frame set. If you want to do a quick and dirty updated prediction, used the position from the line that is flagged. P120614 - There is a brighter star 4 arcsec away (it's a UCAC2 star as well).
http://data.boulder.swri.edu/~layoung/watchlist_20120404_liverpool/0614.pdf moves a bit north -- southern limit goes through mid-US. North of Canary Isl.
WFI (Assafin)
I send 2 fits files, one with a small FOV of 30"x30" centered in the star (attached) and the WFI original image for this sample (7.5'x15'). North is up, East is left, 1 pixel = 0.238 arcseconds. In the large WFI frame, the target is at (x=1042.42 , y=179.53). The WFI fits has 28MB, so I furnish the link below for download.
https://docs.google.com/open?id=0B2p1laCNQ2HjbTlfWlJEaVNibVE
Finder Charts
2012-Apr-04 from Buie
For the best images I have attached a 1 arcmin FOV image centered on the occultation star. In these graphics, the green circle is drawn with the size of the aperture used for the astrometry and its position is the location of the photocenter. The superimposed red line shows the DE421 position of Pluto (geocentric). The center symbol is plotted at the time of the event as listed on Leslie's watchlist email of 2012-04-03 5:48pm MDT. The other symbols are at a spacing of 1 hour. Here are some summary notes from looking at the images:
P120614 - There is a brighter star 4 arcsec away (it's a UCAC2 star as well). http://data.boulder.swri.edu/layoung/watchlist_20120404_finder/p120614.2.png
2012-06-10 from John Kielkopf, Louisville KY 20-inch. R-filter
We observed the Pluto field last night starting from the time it first cleared the trees on our horizon. This confirmed that we can target it with the CDK20 during the event, probably beginning a few minutes before midtime. We may also be able to get it with the RC24. There's new tree growth that obscures the horizon from that telescope now, and we'll cut that back before Wednesday. We won't know until then whether we will have a sight line, or if it's better than from the CDK20. Both telescopes have Apogee U16M cameras and will be running either without a filter or with the "Clear Blue Block" filter we use for faint star exoplanet transit photometry.
FITS images in a Johnson-Cousins R filter are on our website:
http://sharedskies.org/archive/select/planets/pluto/20120614/
The jpg attached here that shows Pluto as of last night and the occultation star for Wednesday.
2012-06-10 from Leslie Young, DENIS I-filter
Stars labeled A-N in right-hand finder of lowest row
RA Dec B R I A 18:35:48.69 -19:17:43.8 16.8 13.7 11.7 -- OCC STAR B 18:35:48.47 -19:17:46.5 13.1 11.1 10.7 -- BRIGHT VERY NEARBY C 18:35:49.09 -19:18:00.7 15.1 12.7 12.7 D 18:35:47.53 -19:17:09.7 16.7 15.0 13.6 E 18:35:46.75 -19:17:13.6 14.0 11.2 10.5 -- GOOD REFERENCE F 18:35:46.80 -19:17:27.8 16.5 14.3 12.9 G 18:35:47.44 -19:15:53.1 15.9 14.5 12.6 H 18:35:46.59 -19:15:36.1 10.8 10.4 10.3 -- ANOTHER GOOD REFERENCE, FARTHER AWAY I 18:35:44.77 -19:15:52.0 14.8 13.0 12.3 J 18:35:41.09 -19:18:12.3 14.4 11.9 10.9 K 18:35:53.45 -19:18:42.6 14.9 13.0 11.7 L 18:35:52.63 -19:18:46.9 16.1 13.8 11.5 M 18:35:52.10 -19:18:58.2 16.4 14.2 12.5 N 18:35:54.80 -19:19:23.5 14.3 11.9 11.3
SNR
| B | V | R | I | Notes | |
| λ | .44 | .55 | .70 | .90 | micron |
| Δλ | .098 | .089 | .22 | .24 | micron |
| f(0) | 6.61e-9 | 3.64e-9 | 1.74e-9 | 8.32e-10 | Absolute spectral irradiance for mag = 0.0, erg cm^{-2} s^{-1} A^{-1} |
| k | 0.4 | 0.2 | 0.1 | 0.08 | Extinction coefficient, mag/airmass |
| QE | 0.75 | 0.96 | 0.90 | 0.39 | Quantum efficiency for PhotonMax, e/photon |
| Z | 7.3e8 | 9.9e8 | 1.8e9 | 5.6e8 | Zero point for 50-cm aperture at X=2.9 airmasses, electron/s qef(0)((λ * 1e − 4) / (hc))(π252)(Δλ * 1e4)(10 − 0.4 * k * 2.9) |
Mag & counts at X=2.9, PhotonMax QE, 50-cm apeture. Approximate "Open" as B+V+R+I, "longpass" as R+I. Pluto R mag from Fink & DiSanti 1988.
| Mag | electron/s | |||||||||
| B | V | R | I | B | V | R | I | Open | Longpass | |
| Pluto mag | 15.2 | 14.4 | 13.4 | 13.6 | 603 | 1722 | 7966 | 2031 | 12323 | 9997 |
| A mag | 16.8 | 15.03 | 13.7 | 11.7 | 138 | 964 | 6043 | 11689 | 18834 | 17732 |
| B mag | 13.1 | 11.7 | 11.1 | 10.7 | 4177 | 20705 | 66262 | 29363 | 120507 | 95624 |
SNR, assuming 10e readnoise, 25 pixels summed, only. SNR = 'A_counts' / sqrt(Pluto_counts + A_counts + B_counts + 10^2*25)
| B | V | R | I | Open | Longpass | |
| Pluto & A | 2.4 | 13.4 | 47 | 92 | 103 | 102 |
| Pluto & A & B | 1.6 | 6.0 | 21 | 55 | 48 | 50 |
Call the cadence the time between exposures (cadence = exposure time + dead time)
It takes about 2.5 seconds to cross Pluto's atmospheric scale height, so the typical measure of data quality is SNR/H, signal-to-noise ratio per scale height.
SNR/H = SNR/image * sqrt(2.5/cadence).
SNR/H > 50, cadence < 1.25 s allows direct retrieval of temperatures per altitude => waves, heating rates. SNR/H > 20, cadence < 2.50 s allows model fits => overall temperature and pressure SNR/H > 5, cadence < 5.00 s can be used for geometric reconstruction
Starlists
Stars for starhopping
List compiled by Larry Wasserman
Star RA (2000) Dec RA (Date) Dec Mag Distance
to Occ * (d)
SAO 186841 = Lambda Sgr = HR 6913 18 27 58.2 -25 25 20 18 28 44.3 -25 24 49 2.8 6.38
SAO 186794 = PPM 268387 = HR 6896 18 25 21.1 -20 32 30 18 26 05.6 -20 32 02 4,1 2,76
SAO 161540 = PPM 234623 = HR 6933 18 30 11.9 -18 43 45 18 30 55.8 -18 43 12 5.5 1.44
SAO 161635 = PPM 234753 = HD 171394 18 35 23.8 -19 16 07 18 36 07.8 -19 15 28 7.0 0.10
Occul star 18 35 48.8 -19 17 43 18 36 32.8 -18 17 04
Same dec, earlier RA
List compiled by Leslie Young.
_RAJ2000 _DEJ2000 RAJ2000 DEJ2000 Vmag B-V a
("h:m:s") ("d:m:s") HR Name HD ("h:m:s") ("d:m:s") (mag) (mag) SpType g
---------- --------- ---- ---------- ------ ---------- --------- ----- ----- -------------------- -
15 12 13.3 -19 47 30 5652 24Iot1Lib 134759 15 12 13.3 -19 47 30 4.54 -0.08 A0pSi *
15 13 19.2 -19 38 51 5656 25Iot2Lib 134967 15 13 19.2 -19 38 51 6.08 0.12 A3Vn
15 31 43.4 -20 09 53 5756 138268 15 31 43.4 -20 09 53 6.22 0.22 A8V *
15 32 36.7 -19 40 14 5762 138413 15 32 36.7 -19 40 14 5.52 0.18 A2m
15 38 54.5 -19 18 07 5814 41 Lib 139446 15 38 54.5 -19 18 07 5.38 0.86 G8III
15 41 56.8 -19 40 44 5838 43Kap Lib 139997 15 41 56.8 -19 40 44 4.74 1.57 M0-IIIb
15 53 20.1 -20 10 02 5902 45Lam Lib 142096 15 53 20.1 -20 10 02 5.03 -0.01 B2.5V *
15 55 00.3 -19 22 59 5915 47 Lib 142378 15 55 00.3 -19 22 59 5.94 -0.01 B5V *
16 05 26.2 -19 48 20 5984 8Bet1Sco 144217 16 05 26.2 -19 48 20 2.62 -0.07 B1V *
16 05 26.5 -19 48 07 5985 8Bet2Sco 144218 16 05 26.5 -19 48 07 4.92 -0.02 B2V *
16 09 55.2 -18 20 27 6012 145100 16 09 55.2 -18 20 27 6.47 0.44 F4V
16 11 58.6 -19 26 59 6026 14Nu Sco 145501 16 11 58.6 -19 26 59 6.30 0.13 B8V+B9VpSi *
16 11 59.7 -19 27 38 6027 14Nu Sco 145502 16 11 59.7 -19 27 38 4.01 0.04 B3V *
16 14 39.1 -18 32 07 6053 145997 16 14 39.1 -18 32 07 6.32 1.09 K2III *
16 19 07.7 -20 13 04 6076 146834 16 19 07.7 -20 13 04 6.29 1.08 K5III *
16 24 06.2 -20 02 15 6104 4Psi Oph 147700 16 24 06.2 -20 02 15 4.50 1.01 K0II-III
16 27 01.4 -18 27 23 6118 7Chi Oph 148184 16 27 01.4 -18 27 23 4.42 0.28 B2IV:pe *
16 41 53.7 -19 55 28 6202 150453 16 41 53.7 -19 55 28 5.57 0.43 F4IV-III
16 57 04.0 -19 32 24 6294 152909 16 57 04.0 -19 32 24 6.27 0.07 B6V+B7V
17 01 51.2 -18 53 08 6321 29 Oph 153727 17 01 51.2 -18 53 08 6.26 1.38 K0III
17 20 34.2 -19 19 58 6441 156846 17 20 34.2 -19 19 58 6.52 0.58 G3IV *
17 24 37.1 -18 26 45 6473 157546 17 24 37.1 -18 26 45 6.21 0.03 B9Vn
17 55 55.0 -18 48 08 6679 163245 17 55 55.0 -18 48 08 6.52 0.05 A4V *
18 11 14.8 -19 50 32 6798 166393 18 11 14.8 -19 50 32 6.36 0.16 A4V *
18 15 30.8 -18 39 41 6825 167356 18 15 30.8 -18 39 41 6.07 0.20 A0Ia *
18 17 28.5 -18 27 48 6841 167771 18 17 28.5 -18 27 48 6.54 0.11 O7III:(n)((f)) *
18 18 43.3 -18 37 10 6848 168021 18 18 43.3 -18 37 10 6.84 0.31 B0Ib *
18 21 23.1 -18 51 36 6863 168608 18 21 23.1 -18 51 36 5.75 0.94 F8I *
18 30 11.9 -18 43 44 6933 170433 18 30 11.9 -18 43 44 5.66 1.06 gK0
18 31 26.3 -18 24 10 6944 170680 18 31 26.3 -18 24 10 5.14 0.00 A0Vp *
18 31 53.3 -19 07 30 6947 170764 18 31 53.3 -19 07 30 6.68 1.13 G1.5Ib *
