Notes for Observers
Note that the reflective coating on the continuum filter does NOT cover
the entire surface. Care must be taken to ensure that when fitting
this filter, the filter sits square and centred in the holder. If
not, light can leak past the edge of the filter. This can be seen
as a very bright streak on the edge of the CCD, e.g. when doing flats.
This can be checked during the day by doing a `dome-flat', with the mirror
covers open and the dome lights on. If there is a problem it will
be immediately evident. Note that this procedure is purely to check
the filters; twilight sky flats are much preferred.
The filters to be used are the Harris R filter (number 39 on the
ING filter database); the 115 Angstrom FWHM filter centred on
6471 Angstroms, purchased for this project by PAJ (not on the ING database)
for continuum observations; and the following H alpha narrow-band
filters: 6570/55 Angstroms (number 61, recession velocities 0-950km/s),
6594/44 Angstroms (number 63, recession velocities 950-2100 km/s), and
6626/44 Angstroms (number 65, recession velocities 2100-3000 km/s).
The exposures to be taken are as follows:
1 x 300 second R-band exposure
3 x 1200 second H exposure
3 x 600 second continuum exposure
The exposures are to be read out in QUICK mode.
If the Major axis of the galaxy is less than 3 arcmin the CCD should be
windowed (1000x1000 sub-array), providing there are enough stars remaining
in the sub-array to align images.
It is possible to keep the bias strip, even with a sub-array.
Set up two windows, e.g. like this:
window 1 1000 1000 500 500
window 2 70 1000 2070 500
The trick is to use the same ystart (500) and ysize (1000 in the
example), the bias strip is then e.g. 2070-2140. You end up with a
fits file which has the bias strip glued to the right.
If windowing make a note of the startx and starty values of the window
Because of the narrow-band filters, it is important to use spectrophotometric
standards. A list of these is kept in the JKT control room in a red
file labelled FLUX STANDARDS.