Triggers: Defining Imaging Sequences

This is the imaging sequence (``trigger'') description from the astrod.conf file:

#       Each trigger has a name, a three-letter-acronym ("tla"), a

# livetime (how long to hold in the queue before giving up), and a

# scripted protocol which describes the kind of observation sequence to

# be performed.  The observations are described compactly with the 

# following vocabulary:

#    js = 'jiggled, short' type of exposure

#    ts = 'tile, short' (ie. tile = rastered 2x2 box around coord.)

#    jm = 'jiggled, medium'

#    tm = 'tile, medium'

#    jl = 'jiggled, long'

#    tl = 'tile, long'

#    aoff = turn current alert off

#    calib = do dark run

#    fr = do focus run

#

#    example: 10jl = take 10 long, jiggled exposures.

#

# Note: the number before each element indicates the number of times to

#       run that element.  If you spevify "12ts", it will take 12 tiled

#       short exposures, covering the entire area only 3 times. (12/4tiles)

#          Name             TLA    Lifetime     Protocol

#          --             --    ----     ----

#

trigger    sky_patrol       sky      0          2jl

trigger    dark_run         drk      0          calib

trigger    focus_run        foc      0          fr

trigger    home_check       hom      0          1js

trigger    twi_flat         twi      0          1jm

trigger    pointing         tpt      0          2jm

trigger    follow_up        fup      0          30jl

trigger    photometry       pht      0          2jl

The information from the configuration file is a good explanation of the format, and the is trigger items available are summarized in Table 4.1. See Section 4.6 for step-by-step instructions for defining and implementing as a guest user your own triggers and three-letter acronyms for supernova searches, AGN monitoring, and other monitoring schemes. A couple of comments should be made about the operation. The lifetime parameter should be set to 0 for normally scheduled triggers. This parameter is only used in burst alerts triggers (see below).

Jiggling is the normal mode of operation. During jiggled exposures a random offset of up to 10 pixels is added to the position of each image. This greatly reduces the number of false detections due to hot pixels.

The special trigger sequence calib indicates a dark run. During a dark run ndark dark exposures are taken of each tshort, tmedium, and tlong exposure times.

The special trigger sequence fr indicates a focus run. During a focus run, images are taken at foc_step intervals in the boundaries defined by foc_lim. For more information on how to create a focus model see the focus how-to documentation.

The special trigger command aoff turns off a current running alert in alertd. Once aoff has been run, any new trigger will interrupt the current observing sequence.

There must be a photometry item in the trigger list for Landolt field alert follow-ups. If this item is missing the scheduler will not start up and an error is logged to /var/log/rotse.log.

# Test triggers

trigger    tla_test_alert   tla      1          2jm,aoff

# -HETE GRB trigger response

trigger    grb_hete_alert   gha      600        10js,10jm,50jl,aoff

trigger    grb_hete_update  ghu      600        10js,10jm,50jl,aoff

trigger    grb_hete_final   ghf      600        60jl,aoff

trigger    grb_hete_ground  ghg      600        60jl,aoff

These are the standard burst alert triggers. Every alert response will be followed by a sequence of follow-up images as defined in Section 4.3.4. For every alert type defined in alertd.conf there must be a corresponding trigger entry in astrod.conf. If a valid burst alert arrives and it is not configured here, then only a sequence of follow-up images will be taken.

The lifetime here specifies the maximum time (in minutes) to wait for a burst field to become available before scrapping the prompt response. A burst field might not be available due to the sun, elevation, or weather. Some bursts in the wrong hemisphere will never become available, but are held in the queue anyway. If a prompt response is deleted, follow-up sequences will be run as soon as the field is available.

Table 4.1: Listing of the various trigger options in astrod.conf, and their description

Abbreviation	Name	Description
js	jiggled, short	short exposures, jiggled $<$10 pixels from field center
ts	tiled, short	short exposures, rastered 2$\times$2 box around field center
jm	jiggled, medium	medium exposures, jiggled
tm	tiled, medium	medium exposures, tiled
jl	jiggled, long	long exposures, jiggled
tl	tiled, long	long exposures, tiled
aoff	alert off	turn system alert mode off
calib	dark run	dark calibration run. ndark dark exposures taken
		for each exposure length
fr	focus run	take evenly spaced focus images of a given field.
		See Section 4.3.3.