Catalogs
The minicam graphical interface allows the observer to supplement the traditional
"target" catalog with additional information to control and sequence all
the components of the observing sequence. The required format is a starbase
table, which is a tab delimited ASCII table, with optional header keywords.
It is possible to import a standard MMT target catalog using the catalog
tool.
The entries for the minicam catalog fall in several categories: Telescope
(traditional target information), Guiding, Archiving, Centering, Exposure,
Observation. Values may appear explicitly as columns or can be specified
as global values for the entire catalog in the header.
Telescope
The Telescope entries are the same as those specified in the MMT catalog:
name,ra,dec,rapm,decpm,pa,equinox.
Guiding
Minicam guiding is provided by the guide ccd, mounted in the focal plane
(but off-axis) along with the 2 science CCD chips. One, or preferably two,
guide stars can be identified on the guide chip and used to provide guiding
corrections to the telescope on a 2 second update time-scale. Due to the
poor cosmetic quality of the guider ccd, it's necessary to take several
bias frames at the guide star location before guiding can be activated.
The observer may specify, in the catalog, whether or not guiding is
desired for a particular exposure. By specifying, "guidedata none", guiding
will be disabled. Alternatively, if the observer requires guiding to be
enabled there are two options. The observer can specify manual, which requests
that the telescope operator select guide stars and enable guiding, while
the GUI pauses waiting for confirmation. Or the observer may specify "guidedata
auto" and the software will automatically select appropriate guide star
coordinates from the UA2 catalog, transmit them to the guide application
and wait for guiding to "lock-on" before starting the exposure.
Archiving
The Telescope Data Center (TDC) provides a complete archive of all minicam
observations. There are 3 required fields necessary to support this archive:
propid, observers, pi. The format for these fields is any "whitespace FREE"
ASCII string.
Centering
The first option to consider is where the target should be centered on
the instrument. The Minicam system provides several macros to so that it's
not necessary to know the special MMT offset parameters. For the keyword
obscen, specify one of the following:
-
mosaic (centered on the gap between the chips)
-
ccd1 (centered on chip 1, at the interface
between amp 1 and 2)
-
ccd2 (centered on chip 2, at the interface
between amp 3 and 4)
-
amp1 (centered on amp 1)
-
amp2 (likewise)
-
amp3 (likewise, this is the preferred placement
for most small objects)
-
amp4 (likewise)
otherwise, the observer may specify the specific azimuth elevation coordinate
pair (in instrument space) in arcseconds.
Exposures and Observations Expansions
The Minicam system defines the terms "exposure" and "observation". An exposure
is defined to be a single data acquisition sequence that produces a single
data file. An observation is defined to consist of 1 or more exposures
of a target. There are many ways to compose a sequence of exposures into
an observation. Some common examples are:
-
Take a sequence of exposures at different exposure times
-
Take a sequence of exposures with different filters
-
Take a sequence of exposures by dithering the telescope offsets.
-
Take a sequence of exposures with different propid's.
The Minicam system provides several mechanisms to compactly describe an
observation sequence.
-
Single expansion
The simplest type of expansion is to specify a space-delimited sequuence
for any of these entries:
-
exptime (exposure times)
-
filts ( filters)
-
observers
-
pi (principal investigator)
-
propid (proposal id)
-
type
-
instaz
-
instel
-
bin
-
equinox
-
guidedata
-
Pair-wise expansions
But there are instances where pairs of these values are actually related,
and then it's necessary to provide lists of the same size to each of the
pair of values:
-
exptime filts
-
instx insty
-
Grid expansions (dithering)
For dithering, the observer can specify parameters to specify a 2-dimensional
dither pattern in instrument coordinates. (The software performs the necessary
conversions to the azimuth/elevation coordinate system needed by the telescope).
-
stepx stepy rot nx ny instrot (instx insty)
Keyword Dictionary
Required Entries
I. Telescope
ra
Requested telescope position, sexagesimal notation. If blank, the telescope
position will not be changed
dec
Requested telescope position, sexagesimal notation. If blank, the telescope
position will not be changed
rapm
Optional proper motion value for telescope position. Suggested value: 0.
decpm
Optional proper motion value for telescope position. Suggested value: 0.
pa
Required position angle for telescope rotator. Suggested values:
-
-180 for declinations > 32 degrees,
-
0 for declinations < 32 degrees.
equinox
Epoch AND coordinate system in which the telescope positions are provided.
Common values:
II. Guiding
guidedata
Required field to specify guiding options:
-
auto - guide star positions will be looked up in the ua2 catalog and provided
automatically to the guider
-
manual - telescope operator will set-up guiding manually by visually inspecting
the guide field
-
none - no guiding for this observation
III. Archiving
The Telescope Data Center (TDC) provides a complete archive of all minicam
observations. There are 3 required fields necessary to support this archive:
observers
Required field to be copied to data header to record observers actually
taking data at the telescope.
propid
Required field to be copied to data header to record proposal ID from the
TAC.
pi
Required field to be copied to data header to record Principal Investigator,
i.e. the person to which this telescope time was assigned.
IV. Exposure
type
Required field specifying the type of exposure. Allowed values:
-
object
-
skyflat
-
zero
-
flat
-
focus
bin
Requested binning of the CCD data. The binning factor will be applied in
both row and column CCD dimensions. Nominal value
for minicam at F9.
exptime
Requested exposure time in seconds.
Alternatively, for the special case of skyflats, the value "auto" may
be used and the software will calculate the necessary exposure time for
the skyflat based on the current date/time.
filts
Requested filters. Filter names may NOT have spaces.
A compound filter is delimited with a "," as shown above
Space delimited filter strings denote iterations. The above will expand
into 3 exposures, each using a different filter.
title
User specified name of field that will be recorded in the data header.
V. Centering
It is possible to specify an instrument orientation in instrument coordinates
x,y,rotation that will get transformed into the required azoff/eloff values
needed by the telescope.
obscen
Requested detector position for the target. Several macros are available
for commonly requested positions. The optical axis of the telescope is
aligned with the upper right corner of the minicam chip mosaic, so a non-zero
offset is required to get the target position onto the minicam detector.
Default value is mosaic (-105 95).
-
Macro Offsets (instaz instel)
-
mosaic (-105 95)
-
ccd1 (-105 140)
-
ccd2 (-105 47)
-
amp1 (-105 168)
-
amp2 (-105 117)
-
amp3 (-105 74)
-
amp4 (-105 23)
Or explicit instaz/instel values can be supplied (previously known as the
MacOffsets).
Advanced (Optional) Entries
VI. Dithering
It may be desirable to take multiple exposures at slightly different positions
to smooth the effects of the chip gaps, etc. The requested dither grid
can be specified with the following set of parameters.
instx
Initial x offset position for the grid in instrument coordinages (arcseconds)
from the obscen. Default value 0 - grid will be around obscen.
insty
Initial y offset position for the grid in instrument coordinages (arcseconds)
from the obscen. Default value 0 - grid will be centered at obscen.
instrot
The instrument rotation angle. For minicam this value is nominally -90
degrees.
stepx
Dither x step size in arcseconds (in instrument coordinates).
stepy
Dither y step size in arcseconds (in instrument coordinates).
rot
Rotation of the dither pattern relative to the instrument axes.
nx
Number of dither grid steps in x
ny
Number of dither grid steps in y
Predefined Catalogs
skyflat
This catalog contains the sky flat observations at different binnings.
There are evening skyflats as well as morning skyflats and they cycle through
the minicam filters in the opposite direction depending on the time of
day. Some or all of the entries can be queued to the gobs application.
bias
This catalog contains entries for bias frames at different binnings. Entries
from the catalog can be queued to the gobs application.
Example Catalogs
Sample 1
Sample 2
Sample 3