Undergraduate ALFALFA

Answers to quick questions

  1. The beginning RA is 13.3115 and the drift ended at 15.0228.
  2. The declinations of the beams are the following:
    • Beam 0: 05° 13' 54"
    • Beam 2: 05° 16' 00"
    • Beam 6: 05° 18' 06"
    • Beam 1: 05° 20' 12"
    • Beam 5: 05° 11' 48"
    • Beam 3: 05° 09' 36"
    • Beam 4: 05° 07' 36"
  3. According to the master list, 22p1 means that it is the 22nd drift and the first pass with declination for beam 0 equal to 05° 13' 54".
  4. When we conduct ALFALFA observations we rotate the array by 19°.
  5. The reason we rotate the array by 19° is so the beams end up equally spaced in declination and every beam sweeps through seven different tracks.
  6. The seven beam tracks ordered in increasing declination are:
    • Beam 4: 05° 07' 36"
    • Beam 3: 05° 09' 42"
    • Beam 5: 05° 11' 48"
    • Beam 0: 05° 13' 54"
    • Beam 2: 05° 16' 00"
    • Beam 6: 05° 18' 06"
    • Beam 1: 05° 20' 12"
  7. In order to find the data file that contains the best drift covering NGC 5363 we need the coordinates of the galaxy. The coordinates of NGC 5363 are
    RA: 13h 56m 07s and dec: 5° 15' 17". The beam track that should show the maximum signal from the galaxy is the one from beam 2. In order to find the data file I looked at Sabrina's log file and each scan was observed for 10 minutes:
    • 0000.fits covers: from 13h31m15s to 13h41m15s.
    • 0001.fits covers: from 13h41m15s to 13h51m15s
    • 0002.fits covers: from 13h51m15s to 14h01m15s
    • 0003.fits covers: from 14h01m15s to 14h11m15s
    • 0004.fits covers: from 14h11m15s to 14h21m15s
    • 0005.fits covers: from 14h21m15s to 14h31m15s
    • 0006.fits covers: from 14h31m15s to 14h41m15s
    • 0007.fits covers: from 14h41m15s to 14h51m15s
    • 0008.fits covers: from 14h51m15s to 15h01m15s
    Since NGC 5363 has the RA mentioned before it is covered by the file 0002.fits file.
  8. The bad beam is number one. I heard that it was only doing one polarization of the two per beam. Also, the power levels for it are very low.
  9. I looked in the NED catalog in beam 1's declination and the RA provided and with a search radius of 3 arcmin. I found two galaxies: NGC 5701 which has a companion whose name is 2MASX J14390840+0521126. NGC 5701's velocity is 1505 Km/s and the other does not have a measured velocity. Probably the HI emission is due to 2MASX J14390840+0521126 because it is the closest one to beam 1 and 6.