RV132 (Astrometric/Geodetic VLBA-132)

                      2018 NOV 14 18:00 DOY 318

                          Notes prepared by
                David Gordon, Ed Himwich and John Gipson
                             NVI/GSFC


Special notes for this experiment
=================================
This session will use the RDBE/DDC/Mark5C 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 now span 560 MHz. The S-band frequencies
are being shifted up by 8 MHz from the last few RV's to try to avoid
RFI in the third S-band channel (2352.75-2360.75 MHZ) at five VLBA stations.
The S-band frquencies for this session will be: 2240.75, 2270.75, 2360.75 
and 2380.75 MHz. 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. 

This session will record 8 8-MHz bandwidth channels using 2-bit sampling, 
as in previous RDV's. The bit rate will be 256 Mbits/sec. The data will be
correlated at the VLBA using the VLBA DiFX software correlator.

There are 4 non-VLBA stations scheduled - HARTRAO, NYALES20, ONSALA60 and 
WETTZELL. These 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 most antennas at the beginning and near the 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  Kp  La  Mk  Nl  Ny  On  Ov  Pt  Sc  Wz
0955+476 18318-180000| 326 338     300 338 335 343 333 300 324 335 336     343|
2008-159 18318-180714|         300 383                     352         372 383|

0955+476 18319-174008| 305 300     300 300 300 305 304 314 331 300 300     331|
2008-159 18319-174728|         355 434                     413         434 433|

We are again using the new '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 increased from 53% to 64%, and 
the average idle time decreased from 21% to 10%. The observing time increases 
most at the faster antennas and least at the slower antennas. 

Purpose
=======
This is the sixth of six coordinated astrometric/geodetic sessions in 2018
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 experiments are being coordinated by the geodetic/astrometric VLBI 
programs of USNO, NASA, and NRAO. The experiments have been designed so that
the same data set may be used by each agency for its particular goals. 

USNO and Bordeaux Observatory will perform imaging and correction for source
structure. These sources will establish a set of core reference sources with
known structure and precisely known positions. These data will provide the 
basis for evaluating the long term stability of the radio reference frame and
the ultimate accuracy of wide angle astrometric measurements of extragalactic
radio sources using VLBI.

NASA and USNO will analyze this data to determine and maintain high accuracy 
terrestrial reference and celestial reference frames. The data will 
incorporate the VLBA stations into the VLBI reference frame through the 
inclusion of other geodetic stations for which we have long histories. This
data will also produce highly accurate Earth orientation results and 
possibly the best nutation results ever produced. 

NASA and NRAO will use these sessions to provide a service to users who 
require high quality positions for a small number of sources. While the 
quality of these results will be high, the observing and data reduction 
overhead required will be minimal because a small number of such sources can
be incorporated into a session of the regular geodetic observations, instead 
of requiring special observations.

Sources for this series of experiments will be selected using the proposed 
approach. For each experiment we will select a set of ~60 sources from the
pool of geodetic, astrometric, and monitoring sources. About 20-30 of these 
will remain the same from experiment to experiment and will be chosen to 
optimize the goals of the three groups. A number of poorly observed and/or 
new requested sources will also be included to obtain or improve their 
positions.


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

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

Schedule file name:  rv132.skd

At the IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2018/rv132):
 Sked file: rv132.skd
 Text file: rv132.txt

At the NRAO/VLBA: 
 VLBA Pointing files:
  rv132crd.br  rv132crd.fd  rv132crd.hn  rv132crd.kp  rv132crd.la
  rv132crd.mk  rv132crd.nl  rv132crd.ov  rv132crd.pt  rv132crd.sc
 Summary file: rv132.sksum
 Sked file: rv132.skd
 Text file: rv132.txt
 Vex file:  rv132.vex

This experiment uses the 10 VLBA stations and 4 IVS stations. The IVS stations
are: HARTRAO, NYALES20, ONSALA60 and WETTZELL. Below is the sked summary. 

 Key:     Br=BR-VLBA    Fd=FD-VLBA    Hh=HARTRAO    Hn=HN-VLBA    Kp=KP-VLBA
          La=LA-VLBA    Mk=MK-VLBA    Nl=NL-VLBA    Ny=NYALES20   On=ONSALA60
          Ov=OV-VLBA    Pt=PIETOWN    Sc=SC-VLBA    Wz=WETTZELL
                   Br   Fd   Hh   Hn   Kp   La   Mk   Nl   Ny   On   Ov   Pt   Sc   Wz  Avg
 % obs. time:      63   64   61   66   63   64   53   64   70   65   63   64   63   70   64
 % cal. time:       5    5    2    4    5    5    4    5    3    3    5    5    4    3    4
 % slew time:      25   25   28   23   25   25   22   24   14   12   24   24   22    8   22
 % idle time:       7    5    8    6    5    5   19    6   12   19    7    5   11   17   10
 total # scans:   436  456  194  376  462  456  366  428  292  225  445  453  344  286  372
 # scans/hour :    18   19    8   16   19   19   15   18   12    9   19   19   14   12   16
 Avg scan (sec):  124  121  271  151  119  121  126  130  206  249  122  123  157  212  158
 # data tracks:    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
 Total TB(M5):   1.73 1.76 1.68 1.81 1.75 1.76 1.47 1.78 1.92 0.00 0.00 0.00 0.00 0.00 1.12

      # OF OBSERVATIONS BY BASELINE
  |  Br   Fd   Hh   Hn   Kp   La   Mk   Nl   Ny   On   Ov   Pt   Sc   Wz  Total
--------------------------------------------------------------------------------
Br|      328   12  228  331  341  284  303  125   40  347  338  186   52    2915
Fd|            22  241  423  438  283  362   85   28  373  439  235   37    3294
Hh|                 63   13   21    0   35  112  154    5   18   71  177     703
Hn|                     218  240  132  291  141   77  190  234  283  110    2448
Kp|                          419  318  338   73   22  411  428  213   23    3230
La|                               283  363   84   30  375  444  234   37    3309
Mk|                                    214   59   16  336  284  126   18    2353
Nl|                                         115   43  303  356  265   62    3050
Ny|                                              127   73   81   97  189    1361
On|                                                    22   29   67  180     835
Ov|                                                        381  182   23    3021
Pt|                                                             229   33    3294
Sc|                                                                   94    2282
Wz|                                                                         1035

 Number of  2-station scans:    1
 Number of  3-station scans:  235
 Number of  4-station scans:  109
 Number of  5-station scans:   52
 Number of  6-station scans:   60
 Number of  7-station scans:   97
 Number of  8-station scans:   94
 Number of  9-station scans:   69
 Number of 10-station scans:   95
 Number of 11-station scans:   29
 Number of 12-station scans:    8
 Number of 13-station scans:    3
 Number of 14-station scans:    0
Total number of scans:          852
Total number of obs:          16565


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

There is an IVS INT01 Intensive session scheduled during RV132. Wettzell 
will drop out from ~18:15 - 19:45 on DOY 318 for this Intensive. There 
will also be a USNO/NRAO UT1 Intensive session, scheduled to start at 
~06:30 UTC (+/- 4 hrs) on DOY 319, using Pietown and MK-VLBA, so these 
stations will drop out for about 100 minutes. The exact time is not fixed,
so it is not scheduled in, but the loss of these two antennas for a short 
period should have only a minimal effect. 


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

There are a total of 80 sources scheduled in this session. Among them, 60
are from the geodetic source list, and 20 are sources with few or no previous
observions in IVS sessions.


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
        1:2 fan-out 
        16 MHz sample rate
        2-bit sampling

This recording mode is designated 256-8(RDV). There is no correlator 
speed-up factor.

The frequency sequence covers 560 MHz at X-band and 140 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  2240.75  3, 5, 7, 9  3100 A 859.25| 2020.0 C1 220.75  9
6 S  2270.75 11,13,15,17  3100 A 829.25| 2020.0 C1 250.75 10
7 S  2360.75 19,21,23,25  3100 A 739.25| 2020.0 C1 340.75 13
8 S  2380.75 27,29,31,33  3100 A 719.25| 2020.0 C1 360.75 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 1N 285.75  3
2 X  8445.75 10,12,14,16  7600 B 845.75| 8080.0 1N 365.75  4
3 X  8805.75 18,20,22,24  9600 D 794.25| 8580.1 3N 225.65  5
4 X  8925.75 26,28,30,32  9600 D 674.25| 8580.1 3N 345.65  6
5 S  2240.75  3, 5, 7, 9  3100 A 859.25| 2020.0 2N 220.75  9
6 S  2270.75 11,13,15,17  3100 A 829.25| 2020.0 2N 250.75 10
7 S  2360.75 19,21,23,25  3100 A 739.25| 2020.0 2N 340.75 13
8 S  2380.75 27,29,31,33  3100 A 719.25| 2020.0 2N 360.75 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  2240.75  3, 5, 7, 9  3100 A 859.25| 2020.0 C1 220.75  9
6 S  2270.75 11,13,15,17  3100 A 829.25| 2020.0 C1 250.75 10
7 S  2360.75 19,21,23,25  3100 A 739.25| 2020.0 D1 340.75 13
8 S  2380.75 27,29,31,33  3100 A 719.25| 2020.0 D1 360.75 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.

 HARTRAO:
  This station uses a DBBC rack.
  Please use the procedures generated by DRUDG. 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.

 NYALES20 and WETTZELL:
  These stations have Mark IV or Mark 5 racks.
  Please use the procedures generated by DRUDG. VCs 3 & 4 are used at
  X-band with IF 1. VCs 5 & 6 are used at X-band with IF 3. VCs 9, 10,
  13 & 14 are used at S-band with IF 2.

 ONSALA60:
  This station uses a DBBC rack.
  Please use the procedures generated by DRUDG. 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.

  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
  valo=..., va=... vblo=... and vb=... commands in the VCSX8
  procedure.


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

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 experiment to the
   ivs-ops mail list. Copy analysts@nrao.edu on your ready message.
5. Send a "start" message soon after you have started recording.
   Copy analysts@nrao.edu on the message.
6. At the end of the experiment, send a "finish" message summarizing
   how the experiment was conducted. Copy analysts@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 cddisin.gsfc.nasa.gov/ivsincoming 
      ftp ivsopar.obspm.fr/ivsincoming
      ftp ivs.bkg.bund.de/ivsincoming


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

This experiment will be correlated at the NRAO/VLBA on the VLBA DiFX software
correlator. Most of the Mark4 stations are now E-transfering their data
to Haystack, where it will be copied 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 the session at their correlator 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.

If you need to ship the media instead, please ship it to Socorro as soon
after the experiment as is practical. It should be shipped to the following
address: 

Socorro address for media shipping:
  VLBA Array Operations Center
  National Radio Astronomy Observatory
  Attn: Juan Cordova
  1003 Lopezville Road
  Socorro, NM 87801
  U.S.A.
  Phone: 575-835-7000

Shipping and VLBA contact information is also given at:
https://science.nrao.edu/facilities/vlba/contact/shipping_information.
Please use one of the recommended shipping companies (FedEx, UPS,
DHL, TNT). Please ship your media to the VLBA the same day the session
ends or the next business day (just like the R1/R4 media is shipped).
If you know that there is going to be a problem sending your media to
the VLBA the same day the session ends or the next business day, please
let us (David.Gordon-1@nasa.gov) know as soon as possible so that we,
along with the VLBA, can determine the best course of action. If you
have any questions or comments, please let us know.