General principles of Phase 2 (PH2)

Abstract -- This document presents the generalities of the Phase 2 tool (PH2) and the basic concepts of QSO observations preparation. This document is not instrument-specific and applies to MegaPrime, WIRCam, and ESPaDOnS.

Keywords -- Purpose of PH2, Technical notes, PH2 interface, the concept of Observations Groups made of IC/C/OB, PI-defined calibrations, Summary, Contact information.

Purpose of PH2

PH2 is a web-based tool that allows PIs of accepted QSO proposals to prepare a full description of their observations. This description is stored in a database, which is used to prepare queues of possible observations. PIs can tell the QSO Team what to observe, how, and sometimes even when.

Technical notes

PH2 interface

The typical PH2 interface is shown below:

You can change the size of all the frames inside PH2 by dragging their side with the mouse.

The concept of Observation Groups -- Observation Groups (OGs) are the entities selected from the database, put in the queues, and executed at the telescope by the Service Observer. This subsection explains which entities make an OG.

The entire architecture of PH2 and its database is based on the concept of Observation Blocks (OB); each OB is made of one (and only one) target, one (or many) instrumental configurations, and one (and only one) set of constraints. Each target, configuration or constraint is a unique entity and has a unique label. A target, configuration, and set of constraints may be used more than once, to define various OBs and OGs. Since it is easier to schedule short observations at the telescope, there is a limit of 2 hours (7200 seconds) for the total integration time of one individual observation block.

  1. Targets can have fixed coordinates (Fixed Targets, or FT), or coordinates defined by ephemeris (Ephemeris Targets, or ET). For each instrument, tools are available to bring up finding charts and refine the pointing or the identification of the target.
  2. An Instrument Configuration (IC) consists of a filter, exposure time, and dithering pattern (for an imager), or an observing mode, exposure time, and Stokes parameter (for ESPaDOnS). An IC can be used in more than one OB and OG, so there is no need to duplicate identical ICs.
  3. Constraints concern the desired Image Quality, sky background level, and airmass range. A set of constraints can be used more than once, so there is no need to duplicate identical sets.

An OB is simply created by picking one target, one or more ICs (for example, an IC for a red filter plus an IC for a blue filter; or the IC for Stokes Q and the IC for Stokes U), and one set of constraints.

To add more flexibility to PH2, the concept of Observation Groups (OG) has been introduced. The interface to prepare the groups is illustrated below. Three different types of OGs are available, as illustrated below:

Each OG can have a comment, which will appear when the database is queried. These comments are extremely helpful, and can include specific additional constraints or repeat information found elsewhere in PH2 (e.g.: "Observe at -1hr < HA < +1hr"; "<0.3mag extinction for this target", "Follow with OG34"; "Double star, pick faint one"; "Observe May 3rd only").

As each OG is created, the remaining I-time is calculated. If you exceed your allocated I-time, you will not be able to save your latest changes.

PI-defined calibrations

PIs are not allowed to define detrend calibrations, for any instrument (biases, darks, any type of flat, comparison exposures). For the imagers, PIs do not need to define photometric calibrations using standard stars for the broad-band filters; this is taken care of by the QSO Team. PIs must define narrow-band calibrations if they need photometric calibrations. ESPaDOnS PIs must define, if needed, spectrophotometric, polarimetric, telluric, or radial velocity calibration stars and observations.


A summary of what has been entered so far for a program is available under "Summary". This summary can be emailed to any number of recipients by entering email addresses in the box found at the top.

Contact information

PIs may contact the QSO Team at any time by email, by using qsoteam -=at=-