1993 February 9
The Peoples Photometer has two channels called Romeo and Juliet and there are two pairs of filter slides in routine use. One pair holds Johnson UBV and Kron-Cousins RI filters; the sixth hole used to contain sources for calibration but these are no longer present. The second pair contain Strömgren uvby filters and broad and narrow H filters. The Romeo and Juliet filter slides are not interchangeable. Decide whether you want to use the Johnson or the Strömgren filter slides and ask your Support Astronomer to mount them for you.
There is convenient software in PPAS for two modes of observing:
The aperture slide has three positions; the middle one (2) is always used for TV viewing. The other positions hold interchangeable plates pierced by pairs of apertures for PP22 or single apertures for PP11. A wide variety of aperture plates is available with apertures from 0.5 to 10 mm.; the JKT scale is 13.8 arcsec/mm. Decide what apertures you want and ask your support astronomer to mount them for you.
The ICS PE3210 should also be left running at all times. Check that it
is running and sign on:
where ABC signifies your initials and 5 is one of the accounts chosen
from the white board which nobody else is using.
SET GR 181
This enables you to dump your data to Exabyte.
and follow the prompts for the f/15 focus and the Peoples Photometer. This leads you in to the PPAS software. You will be using either the UBV or STR photometric systems and the STRSKY mode. You will be prompted for the name of your data file; it is usual to start with a new file for each night and to name it after the day of the month. If you use an old file you must type WARMST.
Check that the pneumatics are working correctly by typing PPTEST. If there are any faults reported tell your support astronomer or call the duty tech.
Check the dark counts by typing DARKCNT. The dark counts should be roughly 4 and 8. The dark slides are not perfectly light-tight and the dark counts apparently rise to about 8,12 when the fluorescent dome lights are on. Run DARKCNT first with the fluorescents on and then with them off and check that there is a distinct drop. This checks that the photometer is light sensitive. If the dark counts are 0,0 you have a real problem so call for help.
USEALL (observer's initials)
and then SETOBJ to form a catalogue of stars and standards you intend to
observe. This last step is not essential as you will gradually build
up a .OBJ file as you enter in the position of each star as you observe
it. The important command is:
where P1 is a convenient sequence name and a typical sequence for P1
U-U-8: B-B-2: V-V-2: R-R-4: I-I-8
which would be suitable for standard stars. You can set up further sequences P2,P3 etc with 2* and 4* the exposures for observing fainter stars. It is best not to have sequences totalling more than a hundred seconds because defective telescope tracking may carry the star (partly) out of the aperture.
The RUN files are not generally used.
SLIDES 1 2 1 1 or SLIDES 1 2 3 1
Depending on whether you want to use the aperture(s) in position 1 or 3. If in doubt use the smaller aperture(s). Turn up the TV gain carefully until you can see the apertures clearly delineated by the twilight sky shining through them. Use the `DRAW CIRCLE' command with the Grinell to delineate the apertures. If you have trouble with the Grinnell you can draw them in with felt tip but this is not so good because of parallax.
SLIDES 1 2 2 1
and turn the TV gain up carefully and you should see the star somewhere in the field. SNAFU the telescope to the Romeo aperture; this is the left hand one on the screen which is designed to be on the telescope axis. When you are satisfied with the centering in the Romeo aperture press the ACK button on the telescope console. Then type SNAFU/A and centre the star in the Juliet aperture. When the star is centered again press ACK a second time. Pressing `NOM' and `A' on the telescope console should place the star in the Romeo and Juliet Apertures. Forget the Juliet aperture if you are only going to use PP11.
DEFSEQ P1 if this the sequence you use for standards
PP22 or PP11 and follow the prompts.