Background

Feige 48 is a pulsating sdB (EC14026) star that has been observed from single sites over the last several seasons. It pulsates in at least 5 modes between 300 and 400 seconds, with 3 main peaks at 344, 347, and 350 seconds. The largest peak has an amplitude of ~6 mmags while the 2 lower modes have amplitudes of ~1 mmag. The primary aims of the current WET campaign are to resolve fully the pulsation frequencies with the hope of identifying modes and to confirm rotationally split modes observed in single site data. This data will also serve as a phase point in our search for secular changes as an indication of evolution.

Observing Instructions

This is one of the more obvious sdB pulsators, though the modes can beat down for several hours. This star is quite far north, but with V=13.5, it easily observable from any size telescope in the WET network

RA             Dec          
11 47 11.3     +61 16 19.9    (2000.0)
     mv=13.5

Run start: Please start your run on an integral multiple of ten seconds (times ending in "0"). Check the computer clock just before the start of a run, synchronizing with your master clock to within 0.1 sec if possible.

Integration times: Use 5 second integration times.

Filters: Use NO filters in any channel.

Guide Stars: Please consult the finder chart. Feige 48 has several stars of comparable brightness in the field. Record your ch2 offsets and telescope plate scale so we can determine exactly which star was observed.

Sky calibration:Observers with 3-channel photometers should record sky in all three channels near the beginning and the end of each run to permit accurate cross calibration. Observers with 2 channel photometers should take sky by moving the telescope. We have sometimes in the past used the channel 2 verniers to measure channel 2 sky (only) but we find this is not really reliable. Try to take sky as often as needed, at least once per 1/2 hour, for 4 or 5 good sky points; more are not needed and cause unwanted data gaps in the light curve of the target star.

Apertures: Please use the smallest aperture consistent with getting data of good quality (e.g. no visible loss of light to the edge of the aperture). A general rule of thumb is to use an aperture approximately 8-10 times the diameter of the seeing disk. Record the size of the aperture (in arcsec) in your observing log.

Control Center: The XCOV 21 control center is at Iowa State University's International Institute of Theoretical and Applied Physics (IITAP).

Contacting the Control Center: Consult the Phone Contact List for information on phone, fax, and email for the control center as well as the other sites for this run.

Time Check: Please do a clock time check each night before taking data and verify your time with HQ at the beginning of the run, and as often during the run as possible. HQ will have an accurate clock available for phone clock checks.

Data Transfer: There are two ways to send your data and logs at the end of each night.

1. By FTP to: wet.physics.iastate.edu
   (Note that this has changed from the previous site of wet.physics.iastate.edu!)
   The username for the FTP site and the password is available through email. This information is only available through email because we have had problems with hackers filling the FTP system in the past. This is not an anonymous FTP transfer, so you will need the username and password to upload your data. If you use the FTP option, load your data into the "wet/incoming/xcov21/" directory.
   
   
2. Via e-mail to: wet.physics.iastate.edu
   

Observing Logs: We ask that you send a copy of your observation log along with the data, at the same time if you can.