Finally got my hands on the Optoma TX 1080 aka EP 1080 projector which Paul Bourke recommends. It had some issues which had to be sorted out before use in the Planetarium.
The Optoma logo - Startup logo had to be made a black screen. Logo capture needed VGA input - it did not capture from S-Video. Supplying a 1920 x 1080 signal, it captured with no issues. Takes a minute or so to capture.
Turn off confirmation - When turning off the projector with the remote, it displays "To turn off, press Power button". Since this should not be displayed during the show, had to work out the turn off using RS232 or network option.
Network control - An RJ45 jack allows the projector to be controlled via an ethernet network. It has a built-in web server, and ip address can be set from the menu. Unfortunately, the manual did not mention that the web server is password protected. Found the password by trial and error, admin for the Administrator login. Once logged in, password can be disabled, so that just pressing login leaving the password field blank logs you in. The interface is not fully compatible with firefox, IE gives best results. Unfortunately, our control machine upstairs does not have a network card, so RS-232 seemed to be the way to go.
RS-232 - Tried many times with Hyperterminal, but did not succeed till, by trial and error, found the following:
(a) The projector needs to be turned on after the computer connects to the RS-232 port via hyperterminal or whatever.
(b) The string to be sent to the projector has a space in it. It should be ~0000 1 and not ~00001
(c) Autoit version 3.3.0 onwards are not compatible with Win98 etc.
(d) The control machine upstairs had no CD-drive, and since it runs Win98FE, needed this driver to recognize the 1 GB Sandisk flash drive.
Once I worked out all these, could get an autoit script to send the On and Off commands using a hyperterminal window which was opened at startup.
Time taken to autodetect - Autodetecting the S-video signal was taking more than a minute. Sending the S-video signal using RS-232 ~0012 9 after 30 seconds does the job - brings up the video in 34 seconds.
Mirror deformation - For using the projector in the mirrordome configuration, the mirror needs some support, without which it deforms under its own weight. Jury-rigged with thermocol, will try again using reduced mirror area.