RV101 (Astrometric/Geodetic VLBA-101)

                      2013 SEPT 11 18:00 DOY 254

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

Important Note:
===============

Beginning with number 100, the 'RDV' sessions are now called the 'RV'
sessions. This was necessary because the VLBA schedules only allow for
5-character project codes, so rdv101 had to be changed to rv101. 


Special notes for this experiment
=================================

This session will use 2-bit sampling again, as in the last few RDV's.
Frequencies and channel bandwidths (8 MHz) are the same as in previous
RDV's. The bit rate will be 256 Mbits/sec. The 8 MHz, 2-bit sampling is 
preferable to 16 MHz, 1-bit sampling because the 16 MHz filters are not 
very good at the non-VLBA stations. The data will be correlated at the 
VLBA using the DiFX software correlator.

There are 4 non-VLBA stations scheduled (MATERA, NYALES20, ONSALA60 and
WESTFORD). These stations should see the "Special operations notes for 
non-VLBA stations" section below for special instructions.

To facilitate fringe-finding, there are several long scans on fairly strong
sources with all antennas at the beginning, in the middle, 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  Hn  Kp  La  Ma  Mk  Nl  Ny  On  Ov  Pt  Sc  Wf
1803+784 13254-180000| 300 300 300 300 300 300 300 300 300 300 300 300 300 300|

2229+695 13255-004812| 200 200 200 200 200 200 200 200 200 200 200 200 200 200|

1803+784 13255-174954| 300 300 300 300 300 300 300 300 300 300 300 300 300 300|


Additional Notes:
  - Two-bit sampling is used.
  - In this RDV, all stations will record on Mark5A/B.
  - The fluxes use our most recent models.


Purpose
=======
This is the fifth of six coordinated astrometric/geodetic sessions in 2013
that use the full 10-station VLBA plus up to 10 geodetic stations capable of
recording VLBA modes. This year's series is a continuation of the highly 
successful RDV series begun in 1997.

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 will analyze this data to determine and maintain a high accuracy 
terrestrial reference frame. 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. The data will also produce the most accurate 
Earth rotation results ever produced. We will use these data to make accurate
absolute measurements of UT1.

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 60-70 sources from the
pool of geodetic, astrometric, and monitoring sources. About 30-40 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:  rv101.skd

On ftp.aoc.nrao.edu (aspen):
 VLBA Pointing files:
   rv101crd.br  rv101crd.fd  rv101crd.hn  rv101crd.kp  rv101crd.la  
   rv101crd.mk  rv101crd.nl  rv101crd.ov  rv101crd.pt  rv101crd.sc
 Summary file: rv101.sksum
 Sked file: rv101.skd
 Text file: rv101.txt
 Vex file:  rv101.vex

At IVS Data Center (ftp://cddisa.gsfc.nasa.gov/vlbi/ivsdata/aux/2013/rv101)
 Sked file: rv101.skd
 Text file: rv101.txt
 Vex file:  rv101.vex


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

 Key:     Br=BR-VLBA    Fd=FD-VLBA    Hn=HN-VLBA    Kp=KP-VLBA    La=LA-VLBA
          Ma=MATERA     Mk=MK-VLBA    Nl=NL-VLBA    Ny=NYALES20   On=ONSALA60
          Ov=OV-VLBA    Pt=PIETOWN    Sc=SC-VLBA    Wf=WESTFORD
                   Br   Fd   Hn   Kp   La   Ma   Mk   Nl   Ny   On   Ov   Pt   Sc   Wf  Avg
 % obs. time:      54   59   50   59   59   44   51   56   42   48   57   59   53   43   52
 % cal. time:       4    4    4    4    4    4    3    4    4    4    4    4    4    4    4
 % slew time:      22   22   25   22   23   31   23   23   21   26   23   23   24   17   24
 % idle time:      19   14   21   14   14   20   21   17   32   22   16   14   18   35   20
 total # scans:   314  326  331  322  324  367  293  331  343  378  319  323  311  319  328
 # scans/hour :    13   14   14   13   14   15   12   14   14   16   13   13   13   13   14
 Avg scan (sec):  148  156  130  159  156  104  151  145  106  109  155  157  147  117  138
 # 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 TBytes:    1.7  1.8  1.6  1.8  1.8  1.4  1.6  1.7  1.3  1.5  1.8  1.8  1.6  1.3  1.6
 Total TB(M5):    1.5  1.6  1.4  1.6  1.6  1.2  1.4  1.5  1.2  1.3  1.6  1.6  1.5  1.2  1.4

      # OF OBSERVATIONS BY BASELINE
  |  Br   Fd   Hn   Kp   La   Ma   Mk   Nl   Ny   On   Ov   Pt   Sc   Wf  Total
--------------------------------------------------------------------------------
Br|      201  189  215  217   43  206  219   80   47  234  217  157  118    2143
Fd|           192  295  301   39  196  243   46   40  248  301  214  125    2441
Hn|                180  195   87  118  253   90   90  162  193  235  204    2188
Kp|                     300   32  214  232   41   34  271  307  193  116    2430
La|                           37  204  250   45   39  266  316  203  126    2499
Ma|                                21   58  259  353   25   37   65  140    1196
Mk|                                    153   60   27  233  205  119   71    1827
Nl|                                          70   59  212  247  232  168    2396
Ny|                                              280   51   45   58  128    1253
On|                                                    29   38   62  143    1241
Ov|                                                        268  168  104    2271
Pt|                                                             201  125    2500
Sc|                                                                  174    2081
Wf|                                                                         1742


 Number of  2-station scans:  157
 Number of  3-station scans:  238
 Number of  4-station scans:  112
 Number of  5-station scans:   47
 Number of  6-station scans:   54
 Number of  7-station scans:   49
 Number of  8-station scans:   48
 Number of  9-station scans:   40
 Number of 10-station scans:   70
 Number of 11-station scans:   31
 Number of 12-station scans:   13
 Number of 13-station scans:   12
 Number of 14-station scans:    9

 Total # of scans, observations:   880    14104


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

There is no INT01 Intensive session scheduled during RV101. But there
will be a USNO/NRAO UT1 Intensive session, scheduled to run at ~06:30 
UTC (+/- 4 hrs), using Pietown and MK-VLBA. Therefore, Pietown and MK-VLBA
will be taken out for about an  hour. The exact time is unkonwn, 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 90 sources scheduled in this session. Among them, 25
sources are from the astrometric monitoring list, 35 are from the geodetic
monitoring list, and 30 are previously observed sources that have only a few
observations or were observed in only one session.


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 490 MHz at X-band and 140 MHz at S-band 
using 4 channels in each band. This span fits in one VLBA receiver passband
but it uses both the high and low parts of the geodetic receivers. Because 
only 8 channels total are available when observing with the VLBA stations, 
a wider spanned bandwidth is not advisable.

The following tables list the setup for the VLBA stations and the Mark4
geodetic stations with Mark IV back ends. These are the SAME frequencies 
used in all the standard RDV/RV sessions.

                                         
                                            ONSALA60,                               
                              VLBA     |    NYALES20, WESTFORD
Chan   Sky     Tracks      LO  IF  BBC |   LO  IF   VC   VC# Patch
1 X  8405.99  2, 4, 6, 8  7900 B 505.99| 8080.0 1 325.99  3    H
2 X  8475.99 10,12,14,16  7900 B 575.99| 8080.0 1 395.99  4    H
3 X  8790.99 18,20,22,24  7900 B 890.99| 8580.1 3 210.89  5    3(H)
4 X  8895.99 26,28,30,32  7900 B 995.99| 8580.1 3 315.89  6    3(H)
5 S  2232.99  3, 5, 7, 9  2900 A 667.01| 2020.0 2 212.99  9    L
6 S  2262.99 11,13,15,17  2900 A 637.01| 2020.0 2 242.99 10    H
7 S  2352.99 19,21,23,25  2900 A 547.01| 2020.0 2 332.99 13    H
8 S  2372.99 27,29,31,33  2900 A 527.01| 2020.0 2 352.99 14    H

                                         
                              VLBA     |         MATERA 
Chan   Sky     Tracks      LO  IF  BBC |   LO  IF   VC   VC# Patch
1 X  8405.99  2, 4, 6, 8  7900 B 505.99| 8080.0 1 325.99  3    H
2 X  8475.99 10,12,14,16  7900 B 575.99| 8080.0 1 395.99  4    H
3 X  8790.99 18,20,22,24  7900 B 890.99| 8580.1 3 210.89  5    3(H)
4 X  8895.99 26,28,30,32  7900 B 995.99| 8580.1 3 315.89  6    3(H)
5 S  2232.99  3, 5, 7, 9  2900 A 667.01| 2020.0 2 212.99  9    L
6 S  2262.99 11,13,15,17  2900 A 637.01| 2020.0 2 242.99 10    H
7 S  2352.99 19,21,23,25  2900 A 547.01| 2020.0 2 332.99 11    H
8 S  2372.99 27,29,31,33  2900 A 527.01| 2020.0 2 352.99 12    H


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

 NYALES20, ONSALA60 and WESTFORD:
  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 B.

 MATERA:
  This station has 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,
  11 & 12 are used at S-band with IF B.


  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.


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 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 files to your normal log file data center. 
   The directories for three possible servers are listed below:
      ftp cddisin.gsfc.nasa.gov/ivsincoming 
      directory on vlbeer:   sep13
      directory on aspen:    /astronomy/sep13/rv101
       or /home/archive/e2e/archive/operations/VLBA/observe/sep13/rv101

   NOTE: If you don't normally use aspen, you should not put your log 
   file on that server. The VLBA correlator knows where to find your 
   log files.


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

This experiment will be correlated at the VLBA on the VLBA-DiFX software
correlator. Disks should be shipped to Socorro as soon after the experiment
as is practical. Ny Alesund may use e-transfer and will need to coordinate 
this with Haystack Observatory.

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). The VLBA needs to process the session at their correlator 
as soon as possible because of limited media. They prefer to have the 
data within one week of the observation, but in no case later than two
weeks after the observation. Therefore, 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 
(ivscc@ivscc.gsfc.nasa.gov and 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.