Stage 01

Next we download the locations of HST. This will be later used for the barycentric correction.


This step needs an internet connection!


At the beginning of every stage we read in again the pcf file located in the work directory.
This ensures that any user-made changes to the pcf file will be considered when running a new stage.
This means that the pcf file in the run directory is ONLY used in Stage 00. The same is true for the fit_par.txt file. So, after running Stage 00, PACMAN does not care anymore about the changes made to the pcf file and the fit_par file in the run directory.

Navigate to your rundir (where is located) in your terminal and type:

python --s01

The script ( will assume that you want to continue the analysis started in the newly created work directory. If you want to use a different work directory instead, you can use the –workdir=’SOME_PATH’ flag when running the script.

After running Stage 01 you should get an output like this:

Successfully reloaded meta file
Starting s01
Retrieving Horizons file for every visit: 100%|##########| 2/2 [00:06<00:00,  2.04s/it]
Saving Metadata
Finished s01

We now accessed the HORIZONS system by JPL and downloaded a file containing the positions of HST during the observations. For that a new directory was created in the run directory called “ancil/horizons”. Two new .txt files where saved there; a Horizons file for each visit. Each file contains the X, Y and Z position of HST relative to the solar system barycenter. The X,Y,Z positions of HST were downloaded for 5 minute intervals starting one hour before the first exposure in the observations and one hour after the observations.

For example, the first of the two horizon files should look like this (due to its length, we just display the first 100 lines):

 Revised: Jul 13, 2022           Hubble Space Telescope                     -48
  Launched: April 24, 1990 [from space shuttle Discovery (STS-31)]
  Deployed: April 25, 1990
  NOTE: HST ephemeris data can be unreliable during times of the following
        space shuttle servicing missions
         Servicing Mission 1 : 1993 (December 02-14)
         Servicing Mission 2 : 1997 (February 11-21)
         Servicing Mission 3A: 1999 (December 19-28)
         Servicing Mission 3B: 2002 (March    01-12)
         Servicing Mission 4 : 2009 (May      11-25)
   Length          : 43.5 ft (13.2 m)   Weight      : 24,500 lb (11,110 kg)
   Maximum Diameter: 14 ft (4.2 m)      Data return : ~120 Gigabytes (GB)/week
 Generic orbit facts:
   Altitude     : 569 km, or 353 miles  Inclination  : 28.5 deg. to equator
   Orbit period : 97 minutes            Orbital speed: 28,000 kph (17500 mph)
   The trajectory here is a concatenation of publicly released JSpOC two-line
   elements. These can usually only be propagated reliably "days" into the
   future, and are updated frequently to maintain accuracy.
Ephemeris / WWW_USER Wed Jul 13 16:09:37 2022 Pasadena, USA      / Horizons
Target body name: Hubble Space Telescope (-48)    {source: hst}
Center body name: Solar System Barycenter (0)     {source: DE441}
Center-site name: BODY CENTER
Start time      : A.D. 2013-Mar-13 11:42:48.7368 TDB
Stop  time      : A.D. 2013-Mar-13 19:09:00.8489 TDB
Step-size       : 5 minutes
Center geodetic : 0.00000000,0.00000000,0.0000000 {E-lon(deg),Lat(deg),Alt(km)}
Center cylindric: 0.00000000,0.00000000,0.0000000 {E-lon(deg),Dxy(km),Dz(km)}
Center radii    : (undefined)                                                  
Output units    : KM-S
Output type     : GEOMETRIC cartesian states
Output format   : 3 (position, velocity, LT, range, range-rate)
Reference frame : ICRF
   X     Y     Z
   VX    VY    VZ
   LT    RG    RR
2456364.988064083 = A.D. 2013-Mar-13 11:42:48.7368 TDB 
 X =-1.476849972746521E+08 Y = 1.657369809499303E+07 Z = 7.180590092799842E+06
 VX= 1.124469772410265E+00 VY=-2.245676223660987E+01 VZ=-1.440991105915669E+01
 LT= 4.962948023132520E+02 RG= 1.487854386781139E+08 RR=-4.313127568567339E+00
2456364.991536305 = A.D. 2013-Mar-13 11:47:48.7368 TDB 
 X =-1.476849537536252E+08 Y = 1.656716248437228E+07 Z = 7.176158351578083E+06
 VX=-9.118630576747235E-01 VY=-2.121219501984723E+01 VZ=-1.508138767636239E+01
 LT= 4.962915170475317E+02 RG= 1.487844537802284E+08 RR=-2.184259483513133E+00
2456364.995008528 = A.D. 2013-Mar-13 11:52:48.7368 TDB 
 X =-1.476855791506236E+08 Y = 1.656090617039779E+07 Z = 7.171576495736407E+06
 VX=-3.294660943901103E+00 VY=-2.061148350626258E+01 VZ=-1.540167705226118E+01
 LT= 4.962905275153122E+02 RG= 1.487841571259321E+08 RR= 2.337262296865778E-01
2456364.998480750 = A.D. 2013-Mar-13 11:57:48.7368 TDB 
 X =-1.476869396743260E+08 Y = 1.655472461298847E+07 Z = 7.166955984718477E+06
 VX=-5.768462163862133E+00 VY=-2.071814865314571E+01 VZ=-1.533684718578484E+01
 LT= 4.962919949007342E+02 RG= 1.487845970370145E+08 RR= 2.681895689377115E+00
2456365.001952972 = A.D. 2013-Mar-13 12:02:48.7368 TDB 
 X =-1.476890228025047E+08 Y = 1.654840555093755E+07 Z = 7.162412267895708E+06
 VX=-8.068677535148430E+00 VY=-2.151972953129114E+01 VZ=-1.489444276409387E+01
 LT= 4.962958175571006E+02 RG= 1.487857430405627E+08 RR= 4.898706921593821E+00
2456365.005425194 = A.D. 2013-Mar-13 12:07:48.7368 TDB 
 X =-1.476917388657589E+08 Y = 1.654175173705737E+07 Z = 7.158052387209601E+06
 VX=-9.950237286473346E+00 VY=-2.292961301426449E+01 VZ=-1.412240486833892E+01
 LT= 4.963016426926215E+02 RG= 1.487874893722587E+08 RR= 6.648293961742688E+00
2456365.008897417 = A.D. 2013-Mar-13 12:12:48.7368 TDB 
 X =-1.476949309063722E+08 Y = 1.653460187961141E+07 Z = 7.153963582236750E+06
 VX=-1.121356628678803E+01 VY=-2.479697627327828E+01 VZ=-1.310356197836737E+01
 LT= 4.963089049493011E+02 RG= 1.487896665420393E+08 RR= 7.745405907794824E+00
2456365.012369639 = A.D. 2013-Mar-13 12:17:48.7368 TDB 
 X =-1.476983915652342E+08 Y = 1.652684757059739E+07 Z = 7.150204108606708E+06
 VX=-1.172508178084518E+01 VY=-2.692326763366362E+01 VZ=-1.194655929304390E+01
 LT= 4.963168871113317E+02 RG= 1.487920595340146E+08 RR= 8.074346481521932E+00
2456365.015841861 = A.D. 2013-Mar-13 12:22:48.7368 TDB 
 X =-1.477018850697651E+08 Y = 1.651844455285367E+07 Z = 7.146797167700890E+06
 VX=-1.143051049044278E+01 VY=-2.908310090745547E+01 VZ=-1.077439552521518E+01
 LT= 4.963247960888963E+02 RG= 1.487944305858390E+08 RR= 7.600405022603083E+00
2456365.019314083 = A.D. 2013-Mar-13 12:27:48.7368 TDB 
 X =-1.477051720369279E+08 Y = 1.650941732398336E+07 Z = 7.143728487808440E+06
 VX=-1.036027436743798E+01 VY=-3.104744861249503E+01 VZ=-9.711730650882064E+00
 LT= 4.963318463208541E+02 RG= 1.487965441922071E+08 RR= 6.373218276238906E+00
2456365.022786305 = A.D. 2013-Mar-13 12:32:48.7368 TDB 
 X =-1.477080346684245E+08 Y = 1.649985667911903E+07 Z = 7.140947764075760E+06
 VX=-8.626702960025234E+00 VY=-3.260721397368414E+01 VZ=-8.872018149580901E+00

The next Stage uses the information in these files to convert from MJD to BJD.


You might have noticed the output “Successfully reloaded meta file” at the beginning of the stage. This means that the pcf in the work directory is being read in again and any changes which have been made to the file between Stage 00 and Stage 01 will be considered. This reloading is being done before running every Stage but Stage 00.