We have spent a considerable amount of time worrying about calibration. In general, we can consistently measure the flux of well known calibrators (such as planets) to within 15% over a very wide range of weather conditions and airmass. In general, planets are used as primary calibrators, and all secondary calibrators are bootstrapped from them. Finding calibrators is a traditional problem in ground-based sub-mm astronomy. Although some of the sources listed below are not well characterized, we include them here in case nothing else is truly available.
Each of the stationary targets below are already programmed as a UIP catalog. If you logged into the UIP via the SHARC account, the catalog should already be loaded. If not, enter the following command in the UIP:
UIP> cat user[SHARC]:sharccal.cat
All UIP entries start with the prefix: PNT_ or CAL_ . You can use the "verify" command to list them all quickly (ie:
UIP> verify CAL_*
PLEASE USE THIS CALIBRATION CATALOG!!!!! This makes it easy for us to search the logs for pointing checks, as well as provides stable coordinates for us to adjust and improve the pointing model.
There are also many objects in the solar system that are useful calibrators, though their fluxes vary. To help the user, we have computed the 350 micron fluxes for these objects using the more detailed information described here. You can download these fluxes via the tarball stored here.. Each file in the distribution has 3 columns: UT date, flux (in Jy), and uncertainty (in percent). Primary calibrators have 0% uncertainty.
Table 1: Solar system calibrators. Load them in the UIP using the "PLANET" command. UIP name is same as object name.
Object name |
Type |
Error |
| Callisto | Moon (Jupiter) | 10% |
| Ceres | Asteroid | 10% |
| Davida | Asteroid | 20% |
| Egeria | Asteroid | 10% |
| Ganymede | Moon (Jupiter) | 10% |
| Juno | Asteroid | 10% |
| Mars | Planet | 0 |
| Neptune | Planet | 0 |
| Pallas | Asteroid | 10% |
| Titan | Moon (Saturn) | 10% |
| Uranus | Planet | 0 |
| Vesta | Asteroid | 10% |
Table 2: Stationary calibrators. Load them in the UIP using the "OBS" command. UIP name is given below.
Object name |
UIP name |
RA |
DEC |
Flux (Jy) |
Comment |
| CIT6 | CAL_CIT6 | 10 | +30 | 2.42 +/- 0.24 | Evolved star |
| CRL618 | CAL_CRL618 | 04 | +36 | 19.4 +/- 1.9 | Evolved star |
| CRL2688 | CAL_CRL2688 | 21 | +36 | 41.6 +/- 4.2 | Evolved star |
| IRC10216 | CAL_IRC10216 | 09 | +13 | 24.4 +/- 2.4 | Evolved star |
| O_CET | CAL_OCETI | 02 | -02 | 2.33 +/- 0.23 | Evolved star |
| OH231.8 | CAL_OH231 | 07 | -14 | 17.6 +/- 1.8 | Evolved star |
| VY CMA | CAL_VYCMA | 07 | -26 | 15.6 +/- 1.8 | Evolved star |
| Arp220 | CAL_ARP220 | 15 | +23 | 10.2 +/- 1.0 | Pointlike galaxy |
| G34.3 | CAL_G34.3 | 18 | +01 | 434 +/- 43 | SF region (extended) |
| GL490 | CAL_GL490 | 03 | +58 | 32.2 +/- 3.2 | YSO |
| HLTau | CAL_HLTAU | 04 | +18 | 15.9 +/- 1.6 | YSO |
| IRAS16293 | CAL_16293m2422 | 16 | -24 | 127 +/- 13 | YSO |
| K-350 | CAL_K350 | 20 | +33 | 129 +/- 14 | SF region |
| L1551 | CAL_L1551 | 04 | 18 | 45.2 +/- 4.5 | YSO |
| NGC2071 | CAL_NGC2071 | 05 | +00 | 60.5 +/- 6.1 | SF region (multiple src.) |
| NGC6334I | ????? | 17 | -36 | 420 +/- 126 | SF region (extended) |
| TWHya | CAL_TWHY | 11 | -34 | 6.13 +/- 0.68 | YSO |
| W30H | CAL_W30H | 02 | +61 | 160 +/- 24 | SF region (extended) |
| W75N | CAL_W75N | 20 | +42 | 267 +/- 27 | SF region |
| 0420-014 | PNT_0420m014 | 04 | -01 | 1 - 5 | Blazar |
| 3C273 | PNT_3C273 | 12 | +02 | 1 - 2 | Blazar |
| 3C345 | PNT_3C345 | 16 | +34 | ~1 | Blazar |
| 3C84 | PNT_3C84 | 03 | +41 | ~1 | Blazar |
| OJ287 | PNT_OJ287 | 08 | +20 | ~1 | Blazar |
1) Evolved stars: Some of these sources have 10-20% long-period variability (Sandell 1994; Jenness et al. 2002), but are otherwise excellent calibration sources. Observed (mean) fluxes are derived from measurements with SHARC II since 2003.
2) Blazars are compact but highly variable. Perhaps useful for pointing, but not flux calibration.