Unlike CCDs, NIR detectors can be read in any arbitrary pixel sequence. As a result new modes are possible (rapid read out of region of interest) and high performance can be achieved (CR rejection). However, this would need more computational complexity.
Dani Maoz reviewed the case for a NIR mission. The ground based gold standard is the VISTA survey from ESO.
Marten was concerned that the primary mission (cosmological SN) may need extensive followup and this mission should be figured out (end to end).
An addtional point noted by Dani was that this mission could also undertake microlensing of the Galactic center in J and H bands. This is seen as a major goal of WFIRST but can be done by such a mission (much cheaper and much sooner!).
As noted above, cooling was seen as a major issue. It is clear that the detectors have to be mainted at 150 K in order to minimize dark current. Fiona pointed out that RHESSI (a SMEX mission) employs cryo-coolers which are quite inexpensive and have done an excellent job (cooling the germanium detectors to 80k; see report.
Dipankar brought to our attention that a group in India (Swarna Ghosh, TIFR/NCRA) looking at a small near-IR satellite for spectroscopy (900 km sun-synch and -80C peltier cooled).
[1] Phinney to talk to Werner about JPL expertise in to ascertain feasability to cool to about 150 K. [2] Dani to hold a telecon sharpening the science case (many felt it is too ambitious now). [3] Someone has to produce a plausible optical design that matches to a 15 micron pixel.
Next, Jayant Murthy summarized the basic issues (telescope, detectors) and also the program he is pushing in India. He noted that Canada (ROUTES) has a flight spare UV detector (from the Astrosat mission). This is 40-mm with 25 micron resolution elements. If these are centroided to say SNR of 4 then one could get 4000 pixels on a side. The total count rate is 10^5 per second and the lifetime volume is 1 Coulomb.
C. Martin and P. Morrissey (guests) noted continued improvments in UV detectors. Specifically the pixel size comparable to the bore size or 5 microns can be achieved. Morrissey felt that fiber coupled detectors are now very reliable and we should consider them.
Marten to talk with Ottawa-based ROUTES and send a summary of their latest capability in UV detectors .
One issue that became clear is the complexity of telescope optical design for large FOV. Schmidt telescopes achieve an FOV of 40 square degrees but involve refracting optics. C. Martin noted that Galex used every (reflecting) surface to achieve 1 square degree FOV. We need to seriously look into an optical design. Sterl Phinney suggested that we give up on quality imaging and agree to get a large FOV at the cost of any reasonable PSF. This should be looked into. Yanik, van Kerkwijk
van Kerkwijk and Kulkarni agreed to look into the total count rate for large FOV UV mission (including diffuse emisison and bright stars not counted by Galex).
C. Martin suggested that we consider at least two bands for a follow up. Kulkarni suggested that one telescope be dedicated for a very low resolution objective grism. This way we get imaging (faint object) and spectroscopy (bright object).
Why not use Swift? Avishay to talk to Neil about this possibility?
We had a quick discussion of X-ray sky monitor projects in the coming decade: MAXI (working well but very bright transients) but it is not very sensitive. SVOM is a mysterious Sino-French mission aimed at wholesome studies of GRBs. This is a Swift-like mission. We agree that it is important to keep track of this mission.
At least one sky monitor (LOBSTER) is being studied for the upcoming Explorer deadline.
Dipankar reviewed the status of Astrosat. He thinks launch is no later than 2011 (perhaps into 2012). We talked about PTF-Astrosat synergy. It was resolved that SRK, Avishay and Fiona will send a 1-page white paper to Dipankar as input to the next Astrosat Science meeting (November 9-10, 2010; IUCAA, Pune, India). Avishay was charged with completing the task.
Fiona then talked about a previously proposed mission (BOLT). This concept used the Rotational Modulator Collimator (RMC) which can localize bright X-ray sources at arcminute precision. The bus is very simple given that it does not need fine pointing. Fiona to circulate the old BOLT proposal. Kulkarni suggested that we have a focused telecon on this topic (after reading the Bolt proposal).
It will be useful to know the opportunities for parasitic launches (around the world) in a typical year. FIONA (to enquire USAF and other US launches) and Waxman (for rest of the world).
He also talked of "internet" communications instead of a fixed ground station to receive signals ( "BGAN " based on INMARSAT). In this approach, the satellite sends data to one of a triplet of geostationary satellites which then beams it back to earth. Users receive data via internet. The data cost for this approach versus traditional ground based station approach is yet to be determined.
Separately IAI is now developing a powerful on-board computer with 10 GBits of memory. This eliminates the need for solid state recorders.