Proposal format: Proposals should include a cover sheet with
Attached should be a scientific justification, description of immediate objective (up to two pages) and a list of planned observations + additional comments.
Sky/seeing-constrained proposals have a smaller chance of being successful. Proposals will be ranked A (must be done), B (will be done if there is enough good weather) and C (won't be done).
Sky brightness definitions:
dark - Moon phase < 35% + Moon phase < 65% when Moon below the horizon
grey - Moon phase 35-65% when Moon in the sky + Moon phase 65-94%
bright - Moon phase > 94%
Current seeing statistics (arcsec):
| Filter | 25%-ile | Median | 75%-ile |
| u | 2.7 | 3.1 | 3.6 |
| v | 2.5 | 2.9 | 3.4 |
| g | 2.2 | 2.7 | 3.4 |
| r | 2.0 | 2.5 | 3.1 |
| i | 1.9 | 2.2 | 2.8 |
| z | 1.8 | 2.1 | 2.6 |
| Hα | 1.6 | 1.7 | 2.0 |
What not to propose for:
Proposers
are expected not to replicate observations carried out in the course of the
public survey. If they have a case for making the public survey prioritise
selected fields for observation during a given semester, they should contact
the SkyMapper team directly. A small number of such requests can be
implemented on a best-effort basis without compromising overall survey
optimisation.
During 2014-2019, the public survey will observe the entire sky at dec<+2 with 6x100 sec in u and v, and with 4x100 sec in griz, reaching depths of approx. 21.5 in uv, 22 in gr, and 21 and 20 in i and z, respectively (5-sigma point source AB magnitudes). On any field the full data set will normally be collected within one season. Until early 2015, a Short Survey with saturation limits of ABmag<10 in all filters had priority.
Proposals are furthermore required not to compete with SkyMapper legacy science projects at ANU, which were defined before the nationalisation of SkyMapper.
Required acknowledgement:
For results emerging from public SkyMapper observing time,
you are required to include the following acknowledgement in your publications:
The national facility capability for SkyMapper has been funded through ARC LIEF grant LE130100104 from the Australian Research Council, awarded to CAASTRO, Monash University and the AAO. SkyMapper is owned and operated by ANU's Research School of Astronomy and Astrophysics.
Phase II-preparations:
Successful
proposers will normally need to supply TOBs ("Telescope Observing Blocks") in
an ASCII file, where each individual exposure is one line. The format must
follow the example:
08:45:00 10:30:00 3RD_PARTY 12:39:25.000,+12:52:00.00,g,0,110,1,99
where the fields are:
UTstart UTend 3RD_PARTY RAhh:mm:ss,Decsdd:mm:ss,filter,PA,texp,f#,p#
This includes a unique exposure number f# (in the range 0-4095) and a project ID p# (which you will be assigned).
Observing overheads:
Time for overheads does not need to be
inlcuded in telescope proposals. Overheads per image range from 20 to 80 sec. 20 sec is routinely achieved without slewing the telescope. Telescope slews include changes on three axes: azimuth, altitude, rotation. The azimuth slew is usually the limiting factor, where a 180 deg slew adds 50 sec. Filter changes do not add to the time.
Observing & Data processing:
SkyMapper observations are scheduled during the afternoon preceding a night. Once the scheduler program is started before twilight the observations proceed purely robotically including bias and twilight calibration calibration frames. The SkyMapper team will process the images through the Science Data Pipeline with a currently unknown delay (in temporal order of the processing workflow) and then provide overscan-subtracted, flatfielded images with a WCS, as well as access to the raw data, bad pixel masks and calibration frames.
SkyMapper technical details:
The SkyMapper mosaic camera contains 32 CCDs of 4096x2048 pixels with a plate scale of ~0.50 arcsec/pixel. There are small gaps between the individual CCDs and the resulting field-of view is 2.37 deg x 2.39 deg. The mosaic fill factor is 91% of a 5.68 sq. deg. field-of-view.
The SkyMapper filter curves (with atmosphere) are:
Note that the u-band filter is shortward of the Hydrogen Balmer break, while the v-band is placed between the Balmer break and the Ca H&K 4000AA-break. Additional information on the filter set can be found in Bessell et al. (2011).
Exposure times and depth:
Due to a high read-out noise (RON) of ~10 e-, short exposures and uv filters are affected by RON. Even in full Moon, noise is sky-dominated only at t > 20 sec in the u-band. Provisional 5-sigma point-source detection limits reached in median seeing in a 100-sec exposure under dark sky are:
| Filter | Saturation ABmag | 5sigma-limit ABmag dark |
| u | 10.0 | 19.5 |
| v | 10.5 | 19.5 |
| g | 13.0 | 21.0 |
| r | 13.0 | 21.0 |
| i | 11.0 | 20.0 |
| z | 10.5 | 19.0 |
Restrictions:
Observations are normally carried out at airmass < 2, unless otherwise specified by the proposal. The dome currently vignettes the telescope aperture at airmass > 2.2, and seeing, transmission and background obviously suffer.
The default position angle for the camera should be 0 degrees, which means that North is Up, irrespective of telescope azimuth, however, other position angles can be specified in the TOB. If the requested angle cannot be reached at the time of observation, the camera will rotate by 180 degrees automatically.
The pointing position of the mosaic is in a chip gap. Survey mode proposals can just use desired field centres, while proposals for large-object imaging should offset by a half chip and centre their main object on one of the central four CCDs. Pointing precision is on the order of 1 arcmin, but has been seen to vary. Dithering is also recommended.
There is significant curvature of the focal plane. By default, best focus is put into a ring around the centre to maximise the area of best focus and minimise the run-away of the FWHM in the corners.