What science has learned so far about

comet C/2012 S1 (ISON)

Measurements or derived quantities, published in technical circulars or via press release

observation date (in 2013) distance from Sun (au) instrument observation or derived quantities reference
Jan. 17/18 5.1 EPOXI tail length in projection > 65,000 km EPOXI Release
Jan. 30 4.9 Swift UVOT Q(H2O) = 60 kg/minute Q(H2O) < ~10^28
Q(dust) = 51 tons/minute
nucleus diameter ~5 km (assuming 10% active surface)
NASA Release
and CBET 3608 (July 30)
Mar. 5 4.6 Lowell 1.1-m Q(CN) = 1.3 x 10^24 -> Q(H2O) = 1...10 x 10^26 IAUC 9254 (March 9) & DPS Abstract
April 10 4.15 Hubble Space Telescope WFC3 nucleus diameter < 4 km
coma diameter = 3100 miles
tail length > 57,000 miles
CBET 3496 (April 25) & STScI Release & DPS Abstract
May 4 3.9 Lowell 1.1-m Q(CN) = 2.2 x 10^24 IAUC 9257 (8 May) & DPS Abstract
May 8 3.81 HST The central region of the image shows a polarization p ~ 2.0 - 2.5% DPS Abstract
May 18 (and 24) 3.7 (and 3.6) IRTF NIR spectrum "generally featureless with no diagnostic absorption features [...] consistent with a coma dominated by [...] micron-sized grains" CBET 3622 (8 August)
June 13 3.35 Spitzer Space Telescope Q(CO2) = 2 x 10^26 or Q(CO) = 2 x 10^27
Q(dust) = 55,000 tons/day
CBET 3598 (July 24) & JPL Release & DPS Abstract
June 14-15 3.3 JCMT Q(CO) < 6.4 x 10^27 DPS Abstract
Sep. 14 1.95 Lowell 1.1-m Q(H2O) = 1.1 x 10^28; Q(CN) = 1.1 x 10^25; Q(C2) = 2.0 x 10^25 IAUC 9260 (Sep. 20)
Oct. 4 1.58 Lowell 1.1-m Q(H2O) = 1.5 x 10^28 Biver page
Oct. 5-8 1.5 HST + Arecibo Q(H2O) = 2...5 x 10^28 Biver page and CBET 3680 (30 Oct)
Oct. 15 1.4 Nancay Q(H2O) ~ 4 x 10^28 Biver page
Oct. 21 1.2 HST: COS + STIS Q(CO) = 3 x 10^26; Q(H2O) = 2 x 10^28 CBET 3680 (Oct. 30)
Oct. 22 1.2 Keck: NIRSPEC Q(H2O) ~ 1.4 x 10^28 IAUC 9261 (Oct. 29)
Oct. 24/25 1.2 Keck: NIRSPEC Q(H2O) = 1.2/1.6 x 10^28 IAUC 9261 (Oct. 29)

Other ISON data in circulars and publications

Swift photometry and upper limits fpr Q(H2O) from Jan. til May: CBET 3608 (July 30)
Lowell detection of sunward feature in the coma from March til May: DPS Abstract (October)

Other notable press releases (without hard numbers)

Liverpool Telescope Press Release of April 10 (planning for 2-m telescope)
Gemini Release of May 30 (pictures, general trends)

More findings (and updates/corrections; other lists here and here) to Daniel Fischer, please!