The Prime Minister of India will watch the launch on Sept 9 "from 9:20am to 9:50am" (LT) (0350-0420UTC)
(source)
The Prime Minister of India will watch the launch on Sept 9 "scheduled for 9:50 am" (LT) (0420UTC)
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source)
I've had another look at the "100th mission" claim, and assuming they meant 63 missions instead of 62 (balancing out my earlier point that the number of launches was wrong), that seems to match the number of satellites launched and intended to be operated by ISRO, including INSAT and joint missions with other organisations:
This includes the four commercially procured INSAT-1 spacecraft and INSAT-2DT which was purchased from Arabsat long after launch, counts Chandrayaan 1 and MIP separately, includes the avionics experiment on PSLV C8, and includes seven satellites which failed to orbit (the first Rohini, SROSS-A, SROSS-B, IRS-1E, INSAT-4C, GSAT-4 and GSAT-5P) and Rohini 2 and GSAT-1 which were placed into completely unusable orbits.
It also includes some satellites performing the same "mission"; such as INSAT-4CR, which was essentially a reflight of 4C after the failure.
Furthermore, the launch count makes no distinction between launches carrying satellites that have already been counted, and ones which are not. Every launch India has ever conducted has carried one or more ISRO-operated spacecraft. PSLV-C8 is the only launch to date which has not carried an ISRO satellite as its primary payload, and that flight carried the aforementioned AAM payload. Incidentally the only ISRO payload on the SPOT-6 launch is mRESINS, which is another avionics experiment.
EDIT: I forgot TecSAR - there has been one launch without an Indian payload
If the criteria are adjusted to avoid counting launch and operation separately for the same satellite, and eliminating complete failures, I would give the number of missions actually conducted by ISRO to be 54. ISRO would probably give that as 55, as they do not acknowledge that GSAT-1 failed.
NOTAM confirming the launch time slot (with margins
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A1700/12 - REF NOTAM A1628/12 OF VOMM. PSLV-C21 ROCKET LAUNCH FM SHAR RANGE, SRIHARIKOTA IS SKED ON 09 SEP 2012 BTN 0345 UTC AND 0600 UTC. ATC MAY RE-ROUTE TFC DRG THE PERIOD AS PER ROUTINGS GIVEN IN NOTAM A1628/12 OF VOMM. LAUNCH WINDOW FOR THE REMAINING PERIOD FM 10 SEP TO 04 OCT 2012 SHALL BE KEPT ALIVE FOR RESCHEDULING OF LAUNCH IF REQUIRED. GND - UNL, 09 SEP 03:45 2012 UNTIL 09 SEP 06:00 2012. CREATED: 06 SEP 14:25 2012
Countdown Status
51 hours countdown of PSLV-C21 Mission started at 06:51 hours IST today (September 7, 2012) at Satish Dhawan Space Center (SDSC), Shriharikota, India
Propellant filling operations of Fourth Stage (PS4) and Reaction Control Thrusters (RCT) started at 09:00 hours IST and are under progress.
http://www.isro.org/pslv-c21/status.aspx
Countdown Status
Propellant filling operations of Fourth Stage (PS4) and Reaction Control Thrusters (RCT) completed.
Preparation for Propellant filling operation of Second Stage (PS2) is under progress.
Countdown Status
Preparation for Mobile Service Tower (MST) withdrawal is under progress.
Mobile Service Tower (MST) withdrawal upto 50 meter is completed.
Propellant filling operation of Second Stage (PS2) under progress.
Propellant filling operation of Second Stage (PS2) completed.
System normal, as per timeline.
I've got nothing on the first link. Second link works for me.
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