Tirgo CDR Handling

We will describe the basic user operations for Tirgo Nicmos3 data handling as well as data format and telescope archiving items. We will cover the following items:

Data Structure

All data taken with Tirgo Nicmos3 instruments (Arnica and Longsp) are stored directly as standard FITS files at 16 bits integer format.

Every file has an unique name formed from the last 4 digits of the integer part of current Julian date and from 4 digit of a sequencial number. The acquisition program never rewrites over an old file. If program is forced to send data to an existing file, it increments automatically the sequential number until it get a not already used filename. Sequencial number is protected from casual user, and should be changed only for special purposes. To each file is associated an one line description, accessible to DOS dir or in the file "lista.txt" on other systems. The comment contains source name, integration time, and, if telescope is connected, also the coordinates with a limited precision. An example in table 1.

 Volume in drive D is ULTERIORE      Serial number is 3713:19EE
 Directory of  d:\arnica\data\*.*

95130049.fts   135360   6-10-94  16:50 NGC4590 K -4.0s 12.39.30 -26.45.1
95130050.fts   135360   6-10-94  16:50 NGC4590#00 K -4.0s 12.39.30 -26.45.1
95130051.fts   135360   6-10-94  16:51 NGC4590#05 K -4.0s 12.39.30 -26.45.1
95130052.fts   135360   6-10-94  16:51 NGC4590#07 K -4.0s 12.39.30 -26.45.1
95130053.fts   135360   6-10-94  16:51 NGC4590#08 K -4.0s 12.39.30 -26.45.1
   1,218,708 bytes in 5 file(s)         1,257,472 bytes allocated
 120,770,560 bytes free

Data are stored in a working directory. Due to limitation of Dos, the more files are present there, the slower is the processing of a new file. After having collected a between 50 to 100 data files, observer should use a 4Dos procedure (savedata) to move data files to a different location.

We have chosed to include in the fits header all relevant informations available to the system, as source name, telescope position and so on. That choise is intended as an help in the reduction phase and as the backbone of the forthcoming Tirgo data archive. We give here an example.

  SIMPLE  =                    T
  BITPIX  =                   16
  NAXIS   =                    2
  NAXIS1  =                  256
  NAXIS2  =                  256
  ORIGIN  = 'T I R G O'            / TIRGO Observatory
  BSCALE  =        1.0000000E+00   / real_value = tape_value * BSCALE + BZERO
  BZERO   =        0.0000000E+00   / real_value = tape_value * BSCALE + BZERO
  BUNIT   = 'COUNTS'               / Each count corresponds to  19  electrons
  OBJECT  = 'NGC4590'              / Identifier of source
  DATE-OBS= ' 10/06/94'            / UT date of data acquisition
  TIME-OBS= ' 15:49:55'            / UT Time of data acquisition
  J-DAY   =        9.5131597E+03   / Julia n date of acquisition minus 2440000
  DATE    = ' 10/06/94'            / UT date this file was written
  NUMBER  =                   49   / Incremental acquisition number
  INSTRUME= 'ARNICA    '           / Device who measured data
  OBSERVER= '    Carlo_Baffa'      / Observer name
  FILTER  = ' K 1200 '             / Filter name and wheel position
  TIME-INT=        1.0000000E+00   / Integration time on detector  1.0 * 4
  COADDS  =                    4   / Number of frames added togheter
  RA      = '12.39.30,0'           / Right ascension of source
  DEC     = '-26.45.10'            / Declination     of source
  EPOCH   =        1.9500000E+03   / Epoch of coordinates
  AIRMASS =        2.3000000E+00   / Airmass when acquisition started
  DATAMIN =        9.1000000E+01   / minimum value in array
  DATAMAX =        9.9990000E+03   / maximum value in array
  DOUBLESA= 'ON '                  / Double sampling enabled

Data handling during measurements

Data are stored in a working directory. Due to limitation of Dos, the more files are present there, the slower is the processing of a new file. After having collected a between 50 to 100 data files, observer should use a 4Dos procedure (d:\ir_soft\bin\savedata) to move data files to a more suitable location. The command savedata has no arguments and is automatically executed by xnir from time to time, but is resposibility of the observer to monitor its activity and, if it is the case, to execute manually. savedata must also be executed manually at the endo of a night. If the acquisition program is running inside DVX, can be called from a normal dos window, precede (only one time) by the command cdd d:\ir_soft\bin.

Data will be moved in a directory belonging to a tree of directories which permits to separate easily data of different dates, as in the followin table. Each savedata creates a new subdirectory in the present day directory. The present version limit the number of subdirectory of each day to 14.

                                  |   +---1
                                  |   +---2

Permanent Data Archiving on CDR

At the end of each night, data must be moved to a removable media, as a CD Writable disk (CDR) or a JAZ cartridge. At TIRGO, at present, the CD writer is not working due to low pressure problems, so JAZ cartridge should be used. That media is only temporary, and data are transferred to a more permanend support (the CDR) at Arcetri. The responsible of tranfers is A. Margaglio. Night assistants must take care to have a cartridge with enough free space, and to borrow to Arcetri when reasonably filled up.

Observer must switch on the external Jaz or CDR box and reset the arnica pc. Then he/she must place the current CDR or JAZ cartridge in the slot and run the procedure trandata which will automatically copy data. We strongly suggest the observer to execute the save procedure at the end of each night: it will take about 20 minutes for CDR ad about 10 minutes for JAZ.

trandata must be run outside DVX environments. Trandata will display informations the quantity of data to be transferred and ask to select JAZ (answer Y) or CDR (answer N). If media free space is low, data should go to next cartridge. The screen should appare as:

If the current media is CDR, the program asks if there is need to initialize the cartridge. The initialization procedure is complitely automatized and take about 5 minutes. Do not re-initialize a disk! Do not initialize a cartridge for a later use without writing some data on it: it is probable that computer will not mount it again!

The cartridge is now mounted for writing. The program display a day-based summary of current month data. Data already transferred (even if partially) are marked moved. The user can select the day or the days to be copied by means of <space bar> and can start execution with <enter>. In the following screenshot days SEP_1 and SEP_2 have been already processed and the day SEP_3 is selected to be copied.

At the end of the copy, which take about 10 to 20 minutes for each day transferred, the procedure asks if the copy has be done properly and, if it has to delete data from the hard disk. Too many data sitting on hard disk will slow down data acquisition till to stop, so it is observer's cure not to exeed efficiency limit. Also observer can choose to hold on disk all their data and to dump all at once on their own cartridge. Remember to alwais do Tirgo own archive save! Note also that CDR disks written by Tirgo computer can be read in other system only after being finalized.

If the free space on cartridge is low and the current cartridge is a CDR, the program propose to finalize the cartdridge. The process will take few minutes. The finalizing process will convert the CDR cartridge to the ISO-9660 format. The CDR can now be read in all standard CDROM reader by nearly all brand of computer. The finalizing process also permanently write protect the cartridge.

If the copy is interrupted, trandata can be restarted and will not overwrite data already transferred. However, if a CDR cartridge has been damaged, the program will warn the user. Normally in this case, it is necessary to mount manually the CDR by means of the program c:/util/cdrex/cdrex, in interactive mode.

In case of trouble, please contact Carlo Baffa (baffa@arcetri.astro.it).

We mantain an archive of all data taken with our instruments. Data are stored in a series of CD Rom cartridges each containing from about 400 to 600 Mega bytes of data each. Each cartridge contains data of few days of observations, and has a progressive label which identify the sequence as in DATA_9A and DATA_9B (the two sides of an old worm cartridge) or DATA_26 (in the new CDR format). It is a wise idea to annotate on the ufficial logbook the name of the cartridge in use.

After copy completed please leave arnica PC ON and DVX running.

Data are automatically trasferred to cleopatra Linux workstation, under the directory ~tirgo/dati_arnica and from there saved on a DAT cartridge (borrow your own!) with a command like:

tar tvf tirgo:/dev/rst0 sep_97

Small amount of data can be tranferred to home instituton by ftp, remeber that data must be transferred in bin mode.

Observer can also borrow a blank JAZ and fill it with their data by means of trandata procedure.

Last updated 17 Sep 96

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