RV148 (Astrometric/Geodetic VLBA-148)

                      2021 JUL 07 18:00 UTC DOY 188

                      Notes prepared by David Gordon (GMU/USNO)
                       and Ed Himwich (NVI/GSFC)


Special notes for this session:
===============================
This session will use the RDBE/DDC/Mark6 system at the VLBA sites, as
in previous RV sessions. The X-band frequencies are: 8365.75, 8445.75, 
8805.75 and 8925.75 MHz, and spans 560 MHz. The S-band frequencies have
been changed from the last few RV's to accommodate HOBART26. They are:
2212.75, 2242.75, 2282.75 and 2372.75 MHz. It is expected that HOBART26
will get only the first 3 S-band channels due to RFI issues. The ending
in .75 MHz is necessary at the VLBA stations. Therefore it will not be 
possible to monitor phase cals using the 10 kHz filters. 

RV148 will record 8 16-MHz bandwidth channels using 2-bit sampling.
The bit rate will be 512 Mbits/sec. The data will be correlated at the 
VLBA using the VLBA DiFX software correlator.

There are 7 non-VLBA stations scheduled - HARTRAO, HOBART26, NYALE13S, 
NYALES20, ONSALA60, SESHAN25 and WETTZELL. HOBART26, SESHAN25 and NYALE13S
are new this year to the RV sessions. NYALE13S was tagged along in order
to improve the tie with the legacy X/S stations. The 7 non-VLBA stations 
should see the "Special operations notes for non-VLBA stations" section 
below for special instructions. 

To facilitate fringe-finding, there are some long scans on fairly strong 
sources with many antennas near the beginning and end of the schedule. All 
stations please try to be onsource and recording data for these scans. 
These scans are: 

Source      Start      DURATIONS
name     yyddd-hhmmss   Br  Fd  Hh  Hn  Ho  Kp  La  Mk  Nl  Ny  On  Ov  Pt  Sc  Sh  Wz  Ns
0716+714 21188-180000| 319 300     351     302 300 337 331 300 364 310 300 360 357 362 364|
3C274    21188-180725|         300 405                 407 406 392         377     416 416|
0215+015 21188-180801| 322 300         300 317 300 321             318 300     322        |

1803+784 21189-173437| 328 341     309     338 338 300 315 300 541 333 338 316 541 319 349|
3C274    21189-174107|         300 340                 340 362             348     362 362|
0215+015 21189-174152| 323 317         300 317 318 323             319 317                |

We are again using the 'Fill' scheduling option. 'Fill' is run after a 
schedule is finished in the normal manner. It increases the scan times at
stations, when possible, based on how much idle time each station has before 
its next scan. We used a 'FILL_OFF' margin of 5 seconds. Using 'Fill' on the
original schedule, the average observing time increases from 45% to 57%, and 
the average idle time decreases from 24% to 12%. The observing time increases 
most at the faster antennas and least at the slower antennas. 


Purpose
=======
This is the fourth of six coordinated astrometric/geodetic sessions in 2021
that use the full 10-station VLBA plus several geodetic stations capable of
recording VLBA modes. This year's series is a continuation of the highly 
successful RDV series begun in 1997. These are now being run under the USNO's 
VLBA time allocation.

These sessions are being coordinated by the geodetic/astrometric VLBI programs 
of USNO, NASA and NRAO. They have been designed so that the same data set may
be used by each agency for its particular goals.  

Schedule information
====================

This is a new schedule generated by David Gordon at USNO using sked. 

Schedule file name:  rv148.skd

At the IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2021/rv148):
 Sked file: rv148.skd
 Text file: rv148.txt

At the VLBA/NRAO: 
 Sked file: rv148.skd
 Vex file:  rv148.vex
 Text file: rv148.txt
 Summary file: rv148.sksum

This session uses the VLBA stations and 7 IVS stations. The IVS stations are:
HARTRAO, HOBART26, NYALE13S, NYALES20, ONSALA60, SESHAN25 and WETTZELL. NYALE13S
was tagged along. Below is the sked summary. 

 Key:     Br=BR-VLBA    Fd=FD-VLBA    Hh=HARTRAO    Hn=HN-VLBA    Ho=HOBART26
          Kp=KP-VLBA    La=LA-VLBA    Mk=MK-VLBA    Nl=NL-VLBA    Ny=NYALES20
          Ns=NYALE13S   On=ONSALA60   Ov=OV-VLBA    Pt=PIETOWN    Sc=SC-VLBA
          Sh=SESHAN25   Wz=WETTZELL
                   Br   Fd   Hh   Hn   Ho   Kp   La   Mk   Nl   Ny   Ns   On   Ov   Pt   Sc   Sh   Wz  Avg
 % obs. time:      57   60   52   57   53   60   61   53   58   62   50   61   59   61   58   45   61   57
 % cal. time:       6    6    3    5    3    6    6    5    6    5    4    6    6    6    5    4    6    5
 % slew time:      27   27   40   27   31   28   26   28   26   21    2   26   26   27   27   34   13   26
 % idle time:       9    7    5   10   11    6    6   13    9   11   43    6    8    6    9   15   19   12
 total # scans:   486  497  249  475  275  510  498  454  476  451  323  476  496  507  467  372  485  441
 # scans/hour :    20   21   10   20   11   21   21   19   20   19   13   20   21   21   19   16   20   18
 Avg scan (sec):  101  104  179  103  168  101  106  101  106  118  135  111  103  103  107  105  109  114
 # data tracks:    16   16   16   16   16   16   16   16   16   16   16   16   16   16   16   16   16
 # Mk5 tracks:     16   16   16   16   16   16   16   16   16   16   16   16   16   16   16   16   16
 Total TB(M5):   3.14 3.30 2.85 3.15 2.95 3.31 3.36 2.95 0.00 3.41 2.78 3.38 3.27 3.35 3.20 2.49 3.39 2.96

      # OF OBSERVATIONS BY BASELINE
  |  Br   Fd   Hh   Hn   Ho   Kp   La   Mk   Nl   Ny   Ns   On   Ov   Pt   Sc   Sh   Wz  Total
-----------------------------------------------------------------------------------------------
Br|      337    1  309    8  357  370  269  347  179  154  114  384  367  252   78  114    3640
Fd|             5  312    9  444  453  247  357  127  112   92  383  464  325   43   96    3806
Hh|                 11  207    4    4    0   10   21   10   35    0    4   22   78   45     457
Hn|                       0  290  320  160  401  197  168  161  271  308  369   45  167    3489
Ho|                           13    9   36    3   18    4   14   12   11    4  118   19     485
Kp|                               445  290  335  127  106   85  429  473  287   52   86    3823
La|                                    250  369  137  121   99  396  479  314   48  102    3916
Mk|                                         186   98   80   42  321  271  144  134   33    2561
Nl|                                              179  156  139  312  354  350   46  142    3686
Ny|                                                   238  315  129  135  134  158  285    2477
Ns|                                                        207  108  115  121  100  186    1986
On|                                                              79   94  135  130  411    2152
Ov|                                                                  414  248   67   80    3633
Pt|                                                                       302   51   98    3940
Sc|                                                                             18  154    3179
Sh|                                                                                 125    1291
Wz|                                                                                        2143

 Number of  2-station scans:  466
 Number of  3-station scans:  278
 Number of  4-station scans:  132
 Number of  5-station scans:  103
 Number of  6-station scans:   96
 Number of  7-station scans:   65
 Number of  8-station scans:   62
 Number of  9-station scans:   76
 Number of 10-station scans:   96
 Number of 11-station scans:   45
 Number of 12-station scans:   32
 Number of 13-station scans:   29
 Number of 14-station scans:    9
 Number of 15-station scans:    9
 Number of 16-station scans:    0
 Number of 17-station scans:    0
Total number of scans:         1498
Total number of obs:          23332


INTENSIVE BREAKS
================

WETTZELL will drop out from ~18:15-19:45 on DOY 188 to observe the one-hour UT1
Intensive session. And there will probably be a USNO/VLBA Intensive on DOY 189,
in which case HN-VLBA and MK-VLBA will drop out for ~90 minutes.


SOURCE SELECTION
================

There are a total of 83 sources in this session: 60 are from the geodetic 
source list, 6 are southern sources with few observations to be observed on 
the HH-HO baseline, 15 are prospective ecliptic navigation sources and 2 are 
requested sources. 


SCHEDULING ALGORITHMS
=====================

This schedule uses the "SRCEVN SQRT" mode of Sked. In the absence of any
constraints, Sked will preferentially observe strong sources that have high 
visibility. This mode attempts to smooth out the number of observations per
source.


RECORDING MODE and FREQUENCIES 
==============================

The data will be recorded using the following setup:
        8 channels, each 16 Mhz bandwidth
        1:2 fan-out 
        32 MHz sample rate
        2-bit sampling

This recording mode is a modified version of 512-16(RDV). S-band frequencies 
were modified for the RFI situation at HOBART26. There is no correlator 
speed-up factor.

The frequency sequence covers 560 MHz at X-band and 160 MHz at S-band
using 4 channels in each band. At the VLBA, the X-band uses two LO's in 
order to fit into the VLBA 512 MHz passband. At the Mark4 stations, the 
X-band uses both the high and low parts of the geodetic receivers. Because
only 8 channels are available when observing with the VLBA/RDBE/DDC systems,
a wider spanned bandwidth is not advisable.

The following tables list the setup for the VLBA stations and the geodetic
stations with DBBC, Mark IV, Mark 5, and VLBA5 back ends. 

                              VLBA     | HARTRAO
Chan   Sky     Tracks      LO  IF  BBC |   LO   IF  BBC   BBC#
1 X  8365.75  2, 4, 6, 8  7600 B 765.75| 8080.0 A1 285.75  3
2 X  8445.75 10,12,14,16  7600 B 845.75| 8080.0 A1 365.75  4
3 X  8805.75 18,20,22,24  9600 D 794.25| 8080.0 B2 725.75  5
4 X  8925.75 26,28,30,32  9600 D 674.25| 8080.0 B2 845.75  6
5 S  2212.75  3, 5, 7, 9  3100 A 887.25| 2020.0 C1 192.75  9
6 S  2242.75 11,13,15,17  3100 A 857.25| 2020.0 C1 222.75 10
7 S  2282.75 19,21,23,25  3100 A 817.25| 2020.0 C1 262.75 13
8 S  2372.75 27,29,31,33  3100 A 727.25| 2020.0 C1 352.75 14

                              VLBA     | HOBART26
Chan   Sky     Tracks      LO  IF  BBC |   LO   IF  BBC   BBC#
1 X  8365.75  2, 4, 6, 8  7600 B 765.75| 8080.0 A1 285.75  3
2 X  8445.75 10,12,14,16  7600 B 845.75| 8080.0 A1 365.75  4
3 X  8805.75 18,20,22,24  9600 D 794.25| 8080.0 B4 725.75  5
4 X  8925.75 26,28,30,32  9600 D 674.25| 8080.0 B4 845.75  6
5 S  2212.75  3, 5, 7, 9  3100 A 887.25| 2020.0 C2 192.75  9
6 S  2242.75 11,13,15,17  3100 A 857.25| 2020.0 C2 222.75 10
7 S  2282.75 19,21,23,25  3100 A 817.25| 2020.0 D2 262.75 13
8 S  2372.75 27,29,31,33  3100 A 727.25| 2020.0 D2 352.75 14

                              VLBA     | ONSALA60, WETTZELL
Chan   Sky     Tracks      LO  IF  BBC |   LO   IF  BBC   BBC#
1 X  8365.75  2, 4, 6, 8  7600 B 765.75| 8080.0 A1 285.75  3
2 X  8445.75 10,12,14,16  7600 B 845.75| 8080.0 A1 365.75  4
3 X  8805.75 18,20,22,24  9600 D 794.25| 8080.0 B1 725.75  5
4 X  8925.75 26,28,30,32  9600 D 674.25| 8080.0 B1 845.75  6
5 S  2212.75  3, 5, 7, 9  3100 A 887.25| 2020.0 C1 192.75  9
6 S  2242.75 11,13,15,17  3100 A 857.25| 2020.0 C1 222.75 10
7 S  2282.75 19,21,23,25  3100 A 817.25| 2020.0 D1 262.75 13
8 S  2372.75 27,29,31,33  3100 A 727.25| 2020.0 D1 352.75 14

                              VLBA     | NYALES20
Chan   Sky     Tracks      LO  IF  BBC |   LO   IF  BBC   BBC#
1 X  8365.75  2, 4, 6, 8  7600 B 765.75| 8080.0 A1 285.75  3
2 X  8445.75 10,12,14,16  7600 B 845.75| 8080.0 A1 365.75  4
3 X  8805.75 18,20,22,24  9600 D 794.25| 8080.0 B1 725.75  5
4 X  8925.75 26,28,30,32  9600 D 674.25| 8080.0 B1 845.75  6
5 S  2212.75  3, 5, 7, 9  3100 A 887.25| 2020.0 C1 192.75  9
6 S  2242.75 11,13,15,17  3100 A 857.25| 2020.0 C1 222.75 10
7 S  2282.75 19,21,23,25  3100 A 817.25| 2020.0 C1 262.75 13
8 S  2372.75 27,29,31,33  3100 A 727.25| 2020.0 C1 352.75 14

                              VLBA     | NYALES13S
Chan   Sky     Tracks      LO  IF  BBC |   LO   IF  BBC   BBC#
1 X  8365.75  2, 4, 6, 8  7600 B 765.75| 8080.0 A1 285.75  3
2 X  8445.75 10,12,14,16  7600 B 845.75| 8080.0 A1 365.75  4
3 X  8805.75 18,20,22,24  9600 D 794.25| 8080.0 B1 725.75  5
4 X  8925.75 26,28,30,32  9600 D 674.25| 8080.0 B1 845.75  6
5 S  2212.75  3, 5, 7, 9  3100 A 887.25| 1700.0 C1 512.75  9
6 S  2242.75 11,13,15,17  3100 A 857.25| 1700.0 C1 542.75 10
7 S  2282.75 19,21,23,25  3100 A 817.25| 1700.0 D1 582.75 13
8 S  2372.75 27,29,31,33  3100 A 727.25| 1700.0 D1 672.75 14

                              VLBA     | SESHAN25
Chan   Sky     Tracks      LO  IF  BBC |   LO   IF  BBC   BBC#
1 X  8365.75  2, 4, 6, 8  7600 B 765.75| 8100.0 A  265.75  3
2 X  8445.75 10,12,14,16  7600 B 845.75| 8100.0 A  345.75  4
3 X  8805.75 18,20,22,24  9600 D 794.25| 8100.0 B  705.75  5
4 X  8925.75 26,28,30,32  9600 D 674.25| 8100.0 B  825.75  6
5 S  2212.75  3, 5, 7, 9  3100 A 887.25| 2000.0 C  212.75  9
6 S  2242.75 11,13,15,17  3100 A 857.25| 2000.0 C  242.75 10
7 S  2282.75 19,21,23,25  3100 A 817.25| 2000.0 D  282.75 13
8 S  2372.75 27,29,31,33  3100 A 727.25| 2000.0 D  372.75 14


Special operations for non-VLBA stations:
=========================================

 All non-VLBA stations:
  Please note that due to the frequency sequence, phase-cal will not
  be visible with a 10 kHz viewing filter in the USB channels. If you
  have another means to verify phase-cal, please use it. If you have a
  Mark IV Decoder, please contact Ed.Himwich@nasa.gov if you would like
  advice on how to set it up to check phase-cal for this frequency sequence.

  Please check the procedures created by drudg. The discussion below
  represents our best understanding of the station configuration. If
  you find an error, please correct it and let us know so we can
  correct the catalog.

 HARTRAO:
  This station uses a DBBC rack.
  BBCs 3 & 4 are used at X-band with IF A, input 1. BBCs 5 & 6 are
  used at X-band with IF B, input 2. BBCs 9, 10, 13 & 14 are used for
  S-band with IF C, input 1.

 HOBART26:
  This station uses a DBBC rack.
  BBCs 3 & 4 are used at X-band with IF A, input 1. BBCs 5 & 6 are
  used at X-band with IF B, input 4. BBCs 9 & 10 are used for S-band
  with IF C, input 2. BBCs 13 & 14 are used for S-band with IF D,
  input 2.

 WETTZELL:
  This station uses a DBBC rack.
  BBCs 3 & 4 are used at X-band with IF A, input 1. BBCs 5 & 6 are
  used at X-band with IF B, input 1. BBCs 9 & 10 are used for S-band
  with IF C, input 1. BBCs 13 & 14 are used for S-band with IF D,
  input 1.

 ONSALA60:
  This station uses a DBBC rack.
  BBCs 3 & 4 are used at X-band with IF A, input 1. BBCs 5 & 6 are
  used at X-band with IF B, input 1. BBCs 9 & 10 are used for S-band
  with IF C, input 1. BBCs 13 & 14 are used at S-band with IF D, input 1.

 NYALES13:
  This station uses a DBBC rack.
  BBCs 3 & 4 are used at X-band with IF A, input 1. BBCs 5 & 6 are
  used at X-band with IF B, input 1. BBCs 9 & 10 are used for S-band
  with IF C, input 1. BBCs 13 & 14 are used at S-band with IF D, input 1.

 SESHAN25
  The logs from SESHAN25 indicate that the station uses a VLBA5 rack,
  but we are not sure that is correct, please let us know.
  BBCs 3 & 4 are used at X-band with IF A, input NOR. BBCs 5 & 6 are
  used at X-band with IF B, input NOR. BBCs 9 & 10 are used for S-band
  with IF C, input NOR. BBCs 13 & 14 are used at S-band with IF D, input
  NOR.

  For Mark IV racks, the IF3 command in the procedure IFDSX assumes
  that VC3 and VC10 will be patched to High. Please verify that the
  switches for your IF3 module are wired this way, and if they are not
  please edit the IF3 command to change the switches. The standard
  wiring is described in "help=if3". If you have questions about the
  wiring, please contact Brian Corey at Haystack.

  If you wish to record back-up channels, please add appropriate
  instances of bbcxx=..., vcxx=..., valo=..., va=..., vblo=.., and/or
  vb=...  commands to the BBC/VC setup procedure.


CHECKLIST for non-VLBA stations
===============================
Please follow the checklist below to ensure you have done all the
necessary steps for this session:

1. Make .prc file with DRUDG and check them out, or use the procedures
   from the last RV session. Check out parity check procedures.
2. Make the .snp file with DRUDG.
3. Set up your system to monitor the clocks with the "gps-fmout" or
   "fmout-gps" commands. If you have questions about this, please 
   contact Ed Himwich as soon as possible.
4. Send a "ready" message an hour or so before the session to the
   ivs-ops mail list (ivs-ops@lists.nasa.gov). Copy analysts@nrao.edu 
   and vlbiobs@aoc.nrao.edu on your ready message.
5. Send a "start" message soon after you have started recording.
   Copy analysts@nrao.edu and vlbiobs@aoc.nrao.edu on the message.
6. At the end of the session, send a "finish" message summarizing
   how the session was conducted. Copy analysts@nrao.edu and 
   vlbiobs@aoc.nrao.edu on your message.
7. Transfer your log file to your normal IVS data center. 
   The directories for the IVS servers are listed below:
      ftp ivsopar.obspm.fr/ivsincoming
      ftp ivs.bkg.bund.de/ivsincoming


Correlation
===========

This session will be correlated at NRAO/VLBA on the VLBA DiFX software
correlator. The VLBA correlator can now only read Mark6 modules. The Mark4 
stations will need to E-transfer their data to Haystack, where it will be 
copied onto a Mark6 module and shipped to the VLBA in Socorro, New Mexico. 
These stations will need to coordinate this with Haystack Observatory 
(contact: Jason SooHoo at jsoohoo@haystack.mit.edu). The VLBA needs to process
this session as soon as possible because of limited media. So please try to 
set up the E-transfer as soon as possible after the session ends.