Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Mon, 3 Dec 1990 03:05:25 -0500 (EST) Message-ID: <0bKUQQi00VcJ8-rE5t@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 3 Dec 1990 03:04:45 -0500 (EST) Subject: SPACE Digest V12 #618 SPACE Digest Volume 12 : Issue 618 Today's Topics: Re: HST images via anonFTP and SPAN/HEPnet Re: sts35 orbital data NASA Prediction Bulletin Format Re: Photon engine Re: HST images via anonFTP and SPAN/HEPnet Magellan terminology Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 1 Dec 90 20:50:52 GMT From: usc!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!ohstpy!pogge@apple.com Subject: Re: HST images via anonFTP and SPAN/HEPnet In article <1990Dec1.153527.28972@ux1.cso.uiuc.edu>, mcdonald@aries.scs.uiuc.edu (Doug McDonald) writes: > In article <1990Dec1.042815.15386@rice.edu> uk1@spacsun.rice.edu (Paul A. Scowen) writes: >>If the Saturn image you're all talking about is the one that was distributed >>on the first GTO tape then only the first plane has anything on it: they only >>used one WFPC frame to take the shot. That may make extracting it easier for >>the dabbler. >> > It is not difficult to extract all four. What is, apparently, > at least as far as I can tell, is figuring out EXACTLY where each one > is on the sky. I have tried and failed to do so by using the published > FITS papers. There are some parameters that are not listed in the papers. > Not surprising, FITS really only specifies the image format and standardizes the header keywords that tell programs how to decode the data records. Very few header keywords are "required", some are "recommended" (and are standard out of expediency, and they are sensible), the rest are up to the person creating the file. This lack of a fixed lexicon of header cards is on purpose, it endows the format with a fair degree of flexibility ("Flexible Image Transport System..."). Each observatory and reduction package (VISTA, IRAF, Figaro, MIDAS, you name it) has their own families of specialized keywords. HST is no exception. You'll have to go to the documents for the WF/PC to get the meanings of most of the header keywords. Though the on-line comments do give most of the info, the fine details are in the relevant documents. You'll have to write to STScI for those. Please bear in mind that this HST image distribution was intended for people who have HST time assigned, and was set out in an anon-ftp space with the assumption that those for whom they are primarily intended already have both the basic knowledge and/or relevant documents at their disposal. Recreational access to these images by the interested members of the general public is incidental. > DOES ANYBODY KNOW HOW TO DO THIS? If so, please tell me! > > Doug McDonald Hmm, OK Doug, let me see. You could mean one of 2 things. 1) Where the HST was pointed when the image was taken? That's in the FITS header. Here's the section of the Saturn header that has that info RA = 0.2910366E+03 / right ascension of the target (degrees) DEC = -0.2201969E+02 / declination of the target (degrees) there are other header cards which give more detailed pointing info, like: PSANGLV3= 0.2492861E+03 / position angle of v3 axis of HST RTASCSUN= 0.1550832672119E+03 / right ascension of the sun DECLNSUN= 0.1035161304470E+02 / declination of the sun EPOCHSUN= 0.2000000E+04 / epoch of the sun MTFLAG = F / moving target flag EQRADTRG= 0.6033000E+05 / equatorial radius of target FLATNTRG= 0.1076209E+00 / flattening of target NPDECTRG= 0.8354000E+02 / north pole declination of target NPASNTRG= 0.2236000E+03 / north pole right ascension of target ROTRTTRG= 0.2840832E+09 / rotation rate of target etc. You'll have to consult the relevant HST FITS documents for details on what all this means. I haven't got a set handy, or I'd pass along the document numbers. 2) How to position the 4 images so that they form one 1600x1600 image? (this is not definitive, or official...) How to Merge WF/PC Images Into One Large Image ============================================== The key point to remember is that the fiducial pixel is always the first pixel of each image. All four fiducial pixels must surround the "four-corners" intersection of the set. This means that after the first image is laid down, the next three must be first rotated by 90, 180, and 270 degrees (respectively) before merging into the full 1600x1600 image. The origin is set by the order in which the pixels were read out, hence the rotations, as each CCD chip has to be positioned so that the on-chip amplifiers and shift registers are on the outside of the mosaic). This gives the odd appearing order. NB: the windows below are for WF images. The PC images have different boundaries. I don't know what the PC boundaries are yet. Step 0: Create a 1600x1600 array to hold the final merged image Step 1: Window each image to the sizes given below: Image 1: nx=782 ny=772 x0=19 y0=29 Image 2: nx=788 ny=776 x0=13 y0=25 Image 3: nx=780 ny=776 x0=21 y0=25 Image 4: nx=782 ny=772 x0=19 y0=29 This cuts out the residual flat-field crud between the images. Step 2: Translate the windowed images so that the origin of each image segment is [1,1] in array coordinates. This step is to help keep the bookkeeping simple. Another translation must follow the rotations (below) prior to merging the images. Step 3: Rotate the images to the correct orientation. The sense the rotations are COUNTERCLOCKWISE. Image 1: Theta = 0 degrees Image 2: Theta = 90 Image 3: Theta = 180 Image 4: Theta = 270 Step 4: Merge the images with the 1600x1600 array. The origin of each image must correspond to these locations in the final grand array: Image 1: X=801 Y=801 Image 2: X=25 Y=801 Image 3: X=21 Y=25 Image 4: X=801 Y=19 The final mosaic will look like this: +-------+-------+ | | | | 2 | 1 | | | | +-------X-------+ | | | Y | 3 | 4 | | | | | | o-------+-------+ orientation: +----> X where "o" is the origin [1,1] of the 1600x1600 array, and "X" is the four-corners point where the first pixel of each image segment must touch. Given this, it is easy to see how the sense of each rotation goes, and the amount of translation required. The actual N-S/E-W orientation of the images depends on the rotation angle of HST when the images were taken. I haven't rummaged through the header info enough to find out, but it is certainly not the usual North=Up/East=Left orientation a priori. Interested VISTA users can email for a .PRO procedure script that will do the merger. It is based on a more special purpose procedure written by Jon Holtzman. --------------------------------------------------------------------- Richard Pogge | Internet: pogge@bruno.mps.ohio-state.edu Dept. of Astronomy | Bitnet: pogge@ohstpy The Ohio State University | Snail: Columbus, OH 43210 USA --------------------------------------------------------------------- ------------------------------ Date: 1 Dec 90 14:34:05 GMT From: nuchat!buster!lescsse!gamorris@uunet.uu.net (Gary A. Morris) Subject: Re: sts35 orbital data In <9011292119.AA18141@hls.com> trop@hls.com (Troy T. Pummill) writes: >Could someone please post the new orbital elements for sts35.... These are the preliminary elements for launch at 0628 UCT on Dec 2, 1990. A new set will be posted after we have get a post OMS burn state vector, sometime Sunday morning. This information and more was posted on Nov 27 in rec.ham-radio, Message-ID: 5958@crash.cts.com, Subject: STS-35 Shuttle Amateur Radio Experiment (SAREX). --GaryM ============================================================ Keplerian Element Set STS-35 1 00035U 90336.32152778 .00031000 00000-0 22174-3 0 66 2 00035 28.4690 359.2943 0005720 246.6067 119.6564 15.71792660 23 Satellite: STS-35 Epoch time: 90336.32152778 Element set: JSC-006 Inclination: 28.4690 deg Space Shuttle Flight STS-35 RA of node: 359.2943 deg Pre-launch flight profile Eccentricity: .0005720 Keplerian Elements Arg of perigee: 246.6067 deg Launch: 2 DEC 90 06:28 UTC Mean anomaly: 119.6564 deg Mean motion: 15.71792660 rev/day W5RRR Decay rate: 3.10E-04 rev/day^2 NASA Johnson Space Center Epoch rev: 2 ============================================================ Gary Morris Internet: lobster!lescsse!gamorris@menudo.uh.edu Lockheed (LESC), A22 UUCP: lobster!lescsse!gamorris Space Station Freedom NASAmail: gmorris/jsc/nasa Houston, Texas Internet: gmorris@nasamail.nasa.gov N5QWC - PP/ASEL Phone: +1 713 283 5195 -- Gary Morris Internet: lobster!lescsse!gamorris@menudo.uh.edu Lockheed (LESC), A22 UUCP: lobster!lescsse!gamorris Space Station Freedom NASAmail: gmorris/jsc/nasa Houston, Texas Internet: gmorris@nasamail.nasa.gov ------------------------------ Date: 1 Dec 90 22:23:42 GMT From: ncis.tis.llnl.gov!blackbird!tkelso@lll-winken.llnl.gov (TS Kelso) Subject: NASA Prediction Bulletin Format As a service to the satellite user community, the following description of the NASA Prediction Bulletin's two-line orbital element set format is uploaded to sci.space on a monthly basis. The most current orbital elements from the NASA Prediction Bulletins are carried on the Celestial BBS, (513) 427-0674, and are updated several times weekly. Documentation and tracking software are also available on this system. The Celestial BBS may be accessed 24 hours/day at 300, 1200, or 2400 baud using 8 data bits, 1 stop bit, no parity. ============================================================================== Data for each satellite consists of three lines in the following format: AAAAAAAAAAA 1 NNNNNU NNNNNAAA NNNNN.NNNNNNNN +.NNNNNNNN +NNNNN-N +NNNNN-N N NNNNN 2 NNNNN NNN.NNNN NNN.NNNN NNNNNNN NNN.NNNN NNN.NNNN NN.NNNNNNNNNNNNNN Line 1 is a eleven-character name. Lines 2 and 3 are the standard Two-Line Orbital Element Set Format identical to that used by NASA and NORAD. The format description is: Line 2 Column Description 01-01 Line Number of Element Data 03-07 Satellite Number 10-11 International Designator (Last two digits of launch year) 12-14 International Designator (Launch number of the year) 15-17 International Designator (Piece of launch) 19-20 Epoch Year (Last two digits of year) 21-32 Epoch (Julian Day and fractional portion of the day) 34-43 First Time Derivative of the Mean Motion or Ballistic Coefficient (Depending on ephemeris type) 45-52 Second Time Derivative of Mean Motion (decimal point assumed; blank if N/A) 54-61 BSTAR drag term if GP4 general perturbation theory was used. Otherwise, radiation pressure coefficient. (Decimal point assumed) 63-63 Ephemeris type 65-68 Element number 69-69 Check Sum (Modulo 10) (Letters, blanks, periods = 0; minus sign = 1; plus sign = 2) Line 3 Column Description 01-01 Line Number of Element Data 03-07 Satellite Number 09-16 Inclination [Degrees] 18-25 Right Ascension of the Ascending Node [Degrees] 27-33 Eccentricity (decimal point assumed) 35-42 Argument of Perigee [Degrees] 44-51 Mean Anomaly [Degrees] 53-63 Mean Motion [Revs per day] 64-68 Revolution number at epoch [Revs] 69-69 Check Sum (Modulo 10) All other columns are blank or fixed. Example: NOAA 6 1 11416U 86 50.28438588 0.00000140 67960-4 0 5293 2 11416 98.5105 69.3305 0012788 63.2828 296.9658 14.24899292346978 Note that the International Designator fields are usually blank, as issued in the NASA Prediction Bulletins. -- Dr TS Kelso Assistant Professor of Space Operations tkelso@blackbird.afit.af.mil Air Force Institute of Technology ------------------------------ Date: 1 Dec 90 23:03:06 GMT From: swrinde!zaphod.mps.ohio-state.edu!van-bc!ubc-cs!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: Photon engine In article <9012010201.AA05883@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >I can think of one exception to this rule. If you use a "pure" energy source >such as antimatter, and if you have a certain mass budget for fuel plus >reaction mass, then you get marginally more thrust by dedicating the whole >mass to equal quantities of matter and antimatter, to be blasted out as >photons, than by setting aside some additional normal matter as reaction >mass... Uh, the matter/antimatter reaction does not yield photons. Not immediately. If you are reacting matter and antimatter, what you are blasting out is mostly either pions or muons, depending on the size of your engine. Electron plus positron does yield gamma rays. However, proton plus antiproton is a much more complex reaction. The usual immediate result is pions, both charged and uncharged. The uncharged ones decay pretty immediately. The charged ones last long enough that a small antimatter engine can collimate them into an exhaust jet using a magnetic nozzle. They then decay into muons; a big engine would end up collimating the muons with its nozzle instead. After a substantial delay (on the order of a kilometer of travel at the energies involved), the muons too decay. In the long run, everything ends up as gamma rays and neutrinos, but fortunately for antimatter propulsion, a lot of that happens long after the stuff leaves the engine. Charged particles are *much* easier to work with. -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 1 Dec 90 15:35:27 GMT From: julius.cs.uiuc.edu!ux1.cso.uiuc.edu!aries!mcdonald@apple.com (Doug McDonald) Subject: Re: HST images via anonFTP and SPAN/HEPnet In article <1990Dec1.042815.15386@rice.edu> uk1@spacsun.rice.edu (Paul A. Scowen) writes: >If the Saturn image you're all talking about is the one that was distributed >on the first GTO tape then only the first plane has anything on it: they only >used one WFPC frame to take the shot. That may make extracting it easier for >the dabbler. > It is not difficult to extract all four. What is, apparently, at least as far as I can tell, is figuring out EXACTLY where each one is on the sky. I have tried and failed to do so by using the published FITS papers. There are some parameters that are not listed in the papers. DOES ANYBODY KNOW HOW TO DO THIS? If so, please tell me! Doug McDonald ------------------------------ Date: Sat, 01 Dec 90 11:32:06 CST From: "John Schultz" Subject: Magellan terminology I have a few questions about the terminology that Ron Baalke (thanks for the fi ne info!) posts about Magellan. What is the purpose of the star calibrations a nd desaturations that he mentions? I assume that the star calibration is used to either reference the probe with Venus or with Earth (or maybe both). As for the desaturation, I haven't the foggiest. :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: : John Schultz :Disclaimer : I *pay* for this - : : University of Missouri - Columbia :do you think the bureaucracy : : Bitnet : C491153@UMCVMB.Bitnet :cares what I say??? : : Internet : C491153@UMCVMB.Missouri.EDU (128.206.1.1) : :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: : Don't dream it, be it... - Frank N. Furter, "RHPS" : :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ------------------------------ End of SPACE Digest V12 #618 *******************