Phase 1: Application & Science Definition

Contents

Introduction

The LT is available to UK and international astronomers for scientific research. It is, however, also available to students from schools and colleges in the UK and Ireland for educational purposes. See the National Schools Observatory website for detail. A small amount of time is also available to amateur and semi-professional astronomers through our PATAG programme.

To which TAG do I propose?

This is determined by the affiliation of the proposal's Principal Investigator (PI):

Applicants from the University of Southampton should read the JMU TAG notes below for special rules governing access to FrodoSpec.

Proposals from schools and colleges wishing to use the LT for educational purposes are very welcome. Please refer to the National Schools' Observatory web site for further details. A very limited amount of rank C telescope time is also available to non- or semi-professional astronomers through the PATAG programme.

If you are not sure which TAG to propose to, please feel free to contact us for further guidance.

When do I apply?

All prospective PIs must wait until their Telescope Allocation Group (TAG) issues a Call For Proposals for the upcoming semester. The Call gives all relevant details (application procedures, current telescope performance, instruments available, etc.) and usually sets a deadline of 3-4 weeks from date of issue.

The exact date of each Call varies slightly from year to year. Generally:

  • For semester A (1st January - 31st August)
    • expect a Call for Proposals in September/October the previous year
  • For semester B (1st July - 28th February)
    • expect a Call for Proposals in February/March of the same year

Note that although the boundaries between the "A" and "B" semesters is nominally 31st January and 31st of July, we have a "twice yearly/8 month semester" model where there is a two-month overlap period at the end of each semester. This means that, between 1st January and 28th (or 29th) February proposals from outgoing semester B and incoming semester A will remain in the queue. The same applies between 1st July and 31st August, when observations from both semesters A and B may be observed. The goal is to avoid empty queue time at the end of the semester, and maximise the chances of the top ranked proposals being completed.

This means that observations of targets or events observable in January or February may be requested in a semester A or semester B proposal. The same applies to July and August.

The link on the sidebar refers to the STFC PATT Call for Proposals (UK PIs); an internal call will be emailed to JMU staff directly. The Spanish Call for Proposals will be issued by the IAC (further details are given below). International PIs (from non-Spanish or non-UK institutions) may apply for LT time through the Opticon Trans-national Access programme, through the International Scientific Committee (CCI), or through PATT. Again, details are given below.

How much time is available?

The available clear time on the LT is distributed as follows (last updated August 2014):

  • Liverpool JMU staff time: 33%
  • PATT-STFC (UK) time: 33%
  • CAT (Spanish) time: 20% (includes time set aside for Spanish schools observing)
  • International Scientific Committee (CCI) time: 5%
  • NSO (including PATAG) time: 10%

Typically, of the order of 1000 hours is available for allocation by all TAGs combined to proposals ranked A or B; roughly 300 hrs is also awarded as backup time to a number of rank C proposals. The exact amount of time available is listed in the Call for Proposals.

What kind of time should I apply for?

There are five types of timing constraint which control when and how often your targets should be observed. These are FLEXIBLE, FIXED, MONITOR, INTERVAL and PHASED:

  • FLEXIBLE time, as the name implies, means that the observations can be carried out at any time during the semester when the observing conditions are appropriate.
  • MONITOR time is allocated when observations of an object are required at a regular interval.
  • INTERVAL time is where observations are taken as often as possible provided the interval between observations is never less than that specified.
  • PHASED time allows you to make an observation of a target at a particular phase of its periodic cycle. An example might be that you want to observe an eclipsing binary during the eclipse, but you do not mind which orbit during the semester that observation is obtained.
  • FIXED time means that the observations will only be carried out at a specified time, or not at all. This kind of time is suitable for occultations, or observations which must be simultaneous with a scheduled observation on some other facility. However, FIXED time is also very intrusive, since the telescope will override all other groups in an attempt to secure these data. Consequently, a CLEAR NEED FOR FIXED STATUS must be demonstrated in any proposal (a transit observations should, for example, be scheduled as a PHASED observation). Also, no more than 20% of time awarded by any panel should be FIXED time.

Deciding whether an observation is FIXED or FLEXIBLE, or whether MONITORing, INTERVAL, or PHASED observations are required, can be quite tricky; these definitions are not commonly used at other observatories. It is important that you GET THIS RIGHT when preparing your observations in the phase 2. Please don't hesitate to contact us if you have any questions.

For further information, see also this somewhat more detailed description of how the Timing Constraints are used (from the Phase2 guide).

What observing conditions should I apply for?

To allow the telescope to be flexibly scheduled in an efficient manner, PIs must specify the seeing and photometric conditions needed in their proposal. PIs should also indicate the sky brightness limitations of their project. This information may be used by each TAG when allocating time in any given semester.

  • Sky brightness:
    The sky brightness model used at the LT predicts a relative sky brightness (described in terms of magnitudes brighter than the best-case, true-dark sky). This prediction includes contributions from solar position, lunar elevation, lunar phase and lunar separation from telescope pointing. For example, the same sky brightness might derive from a faint twilight sky, a crescent Moon, or a gibbous Moon very low down on the horizon. The telescope would make no distinction between these three scenarios. A page describing the sky brightness model in detail can be found here.
  • Seeing:
    Telescope scheduling is performed using the most recently available seeing estimate. This estimate is based on real-time reductions of recently-taken images. All proposals must therefore include an estimate of the worst seeing conditions (in arcseconds) under which observations would be possible.

  • Photometric conditions:
    All proposals must specify whether Photometric conditions are needed, or whether non-Photometric conditions are acceptible. (However, PLEASE NOTE: when preparing observations in the phase 2, if the user sets a weather constraint to non-photometric, then observations will only be observed in non-photometric conditions. If photometric and non-photometric conditions are acceptible, then a weather constraint for transparency should NOT be set.)
    If Photometric time is awarded by the TAG panel and observations are flagged in the Phase 2 GUI as needing photometric, we will endeavour to observe groups only under photometric conditions. However, users should note that, at the present time, any given night is defined as "photometric" or "non-photometric" at the start of the night by the Duty Officer, based on the weather forecasting and satellite imagery available at that time. The robotic telescope control system is not able to distinguish between photometric and mildly non-photometric conditions during the night. It is therefore possible that some photometric groups may be observed in mildly non-photometric conditions (if thick cloud develops the sky temperature will rise and the telescope will stop taking science data until conditions improve).

Note that broad-band photometric standards are obtained automatically every night, regardless of cloud cover. These are available to all LT users. PIs do not need to include time for photometric standard stars in their proposal.

For further information, see also this somewhat more detailed description of how the Observing Constraints are used (from the Phase2 guide).

Which instruments are available?

It is EXTREMELY IMPORTANT that prospective users ALWAYS refer to the latest Call for Proposals for details of the instruments that are available in any given semester. For shared-risk or non-facility-class instruments, proposers should contact LT Phase 1 Support to discuss the feasibility of their project and/or any possible collaboration arrangements that may be needed before applying to use those instruments.

Pointing and tracking

Please see the current Call for Proposals, or contact LT Phase 1 Support, for up-to-date information on the pointing and tracking capabilities of the LT.

How do I calculate how much time I need?

Overheads

Use the instrument-specific exposure time calculator to determine exposure times (Te) needed. Begin each calculation with a single group initialisation time Ti overhead of 20 seconds. PIs must then add instrument-specific overheads to their overall time request, as outlined below.

IO:O overheads

To the calculated exposure time (Te) and the group initialisation time (Ti), the following overheads must be added:

  • Acquisition time, Ta - time taken to slew the telescope on target. This is 60 seconds.
  • Autoguider acquisition, Tg - only if you nominate to use the autoguider. This is 45 seconds.
  • Filter change time, Tf. This is 15 seconds.
  • Readout time, Tr. Assume that this is 18.5 seconds for 2x2 on-chip binning. This includes 5 seconds at the start of each exposure when FITS header information is sent from the telescope and written to the file header. Please contact us if you are interested in using unbinned mode.
Example
Suppose you have a programme with 21 objects which you wish to observe (guided) for 10 nights in a row, with an exposure time of 60 seconds, through three different filters:
  • For one 60 sec exposure only (i.e. only one filter), the total time T1 is
    T1 = Ti + Ta + Tg + Tf + Te + Tr
    = 20 + 60 + 45 + 15 + 60 + 18.5 = 218.5 sec
  • However for three exposures of the same object, where a different filter is used each time (nf = 3), the total time spent on the object Tobj is:
    Tobj = Ti + Ta + Tg + nf(Tf + Te + Tr)
    = 20 + 60 + 45 + 3(15 + 60 + 18.5) = 405.5 sec
    Note that the slew and guider acquisition time is only applied once; no slewing is required after the first exposure because the telescope is already on target.
  • For twenty-one different objects (nobj=21) slewing between each object, per night for ten nights (nN=10), the total time Ttot is:
    Ttot = nN nobj Tobj
    = 10 x 21 x 405.5 = 85155 sec = 23.7 hours

LIRIC overheads

Please review the LIRIC instrument page for details on overheads with this instrument. Exposure times can be worked out using the exposure calculator with the instrument field set to IO:I for the moment.

MOPTOP overheads

MOPTOP operates comparably to the IO:O imager except that there is essentially zero read-out overhead. Overheads should be included for initialisation, slew, filter changes and optionally the autoguider. See the example IO:O calculation.

  • Initialisation time, Ti - Miscellaneous overheads. 20 seconds.
  • Acquisition time, Ta - Simple slew of telescope on target. 60 seconds.
  • Filter change time, Tf - Every group must have this at least once. 10 seconds.
  • Autoguider acquisition, Tg - Only if you nominate to use the autoguider. 45 seconds.
  • Readout time, Tr. There is no read-out overhead. 0 seconds.

MOPTOP exposure time is referred to as the "duration" time, being the interval between the beginning of the first frame and the end of the last. This is to distinguish it from the individual frames made at the rate of 16 per rotation, whose exposure times differ depending on the rotation speed modes. In the "fast" speed mode the rotation period P = 8s and the individual frame exposure time te = 0.4s, while in "slow" mode P = 80s and te = 4.0s.

The duration time td to achieve an on-sky integration time of at least ti seconds is given by:

\[ t_{d} = P \; \left\lceil\frac{t_{i}}{16 \; t_{e}}\right\rceil , \quad \text{where} \quad \begin{cases} P = 8s, t_{e} = 0.4s \quad \text{in fast mode} \\ P = 80s, t_{e} = 4.0s \quad \text{in slow mode} \end{cases} \]

where ⌈⌉ denotes the ceiling function that rounds up to the nearest integer.

Example

What duration to enter in the Phase2UI when the total integration time requirement is at least 300s in slow mode:

  • This is slow mode so we use P = 80s and te = 4s.
  • Plugging these values and ti = 300s into the above equation gives 400s as the duration to use.
  • This duration ensures 5 rotations, i.e. 5 x 16 x 4 = 320s of integration time, meeting the 300s required.

See the main MOPTOP page for more about total integration time on-sky.

FRODOSpec overheads

Overheads for compulsory and recommended FRODOspec actions are:

  • Initialisation time (Ti, Miscellaneous overheads): 20 seconds.
  • Acquisition time (slewing plus moving the target onto the fibre bundle): 4 minutes
  • Each readout time: 20 seconds
  • Grating change: 20 seconds
  • Xenon arc exposure (recommended for wavelength calibration): 60 seconds
  • Tungsten lamp exposure (recommended for fibre tracing): 60 seconds

SPRAT overheads

Please review the SPRAT instrument page for details on overheads with this instrument.

RISE overheads

No filter-change or readout time overheads need be applied when applying for RISE time; a simple 60 second slew overhead and the universal 20sec initialisation overhead are all that are required. No filter changes are possible, and the readout time is negligible.

Overheads for Multi-instrument Groups

Overheads incurred while changing from one instrument to another are set at 60 seconds.

Minimum Usable Fraction

In addition to total time requested, proposers must specify a Minimum Usable Fraction (MUF) of data that is acceptable. This concept was introduced to help the LT technical team schedule observations effectively, e.g., to decide whether to finish the observations for one programme or to start a new programme that may not be completed.

Proposers are asked to specify the MUF for their programme in the technical case of their phase 1 proposal. For example, the MUF can be used to specify that "any observations would be usable" (MUF=5%), or "a complete or nearly complete sample is essential to achieve the science goals" (MUF=90%). The TAC reserve the right to revise the MUF of successful proposals if deemed appropriate.

Our policy on observing group length & repetition of long groups

Broadly speaking, there are three classes of observation that the robotic LT was designed to cater for:

  • Rapidly fading transients (e.g. GRBs) which require an immediate response from the telescope
  • Monitoring of variables and transients with short observing groups repeated every few hours, days or weeks. (e.g. Novae, SNe, etc.)
  • Monitoring of variables and transients with a single (or a few) long observing groups (e.g. planetary or binary transients)

The telescope scheduler must accommodate all of these observations, often on the same night. Response to a sudden transient like a GRB can of course interrupt the current observation, though typically these transients fade rapidly and the interrupted group can be repeated within a few tens of minutes.

Short observing groups can usually be fit in at some point during the night.

Long groups, on the other hand, can be far more intrusive, especially if they are repeated on consecutive nights. A five or six hour observation would of course limit the availability of the telescope to other projects, especially if this (or a similar) group was repeated on consecutive nights.

Our goal is to accommodate all three modes of observing. For this reason we do not limit the length of individual observing groups, nor the time interval between repeats of groups. However, users should realise that proposals which request multiple long observing groups must be accompanied by a very strong science case. The need for repeating such groups within a few days should also be clearly demonstrated.

Time Allocation Groups are encouraged to bear these issues in mind when allocating time to poorly ranked proposals that are likely to occupy more than 50% of a typical 8-10 hour observing night, or to proposals that are better suited to a classically-scheduled telescope.

Other restrictions and guidance notes

We endeavour to obtain all data requested for programmes allocated time by the TACs. However, proposers must remember that on any given night, a dozen or more astronomers are effectively sharing a single telescope. Compromises may sometimes be necessary, and therefore LT operations staff reserve the right to remove from the scheduler database any observations which seriously interfere with other programmes. If users anticipate any such problems, we STRONGLY RECOMMEND that they contact the LT (see the link on the sidebar) in advance of submitting proposals and/or address these issues specifically in their application technical case.

  • Avoid Bright Stars: A common problem encountered at the LT is grossly saturated stars causing image persistence in CCD images. All users are requested to check the field around their targets for bright stars which could disrupt their own and subsequent observations. Even for short exposures, we recommend avoiding any stars brighter than 8th magnitude, unless the telescope is to be defocused or a very low throughput filter (e.g. u') is to be used.

What happens if my application is successful?

The PIs of successful proposals will be required to prepare their observations before the start of the semester using the LT Phase 2 GUI. Proposers seeking to observe Targets Of Opportunity may submit observing groups shortly after the ToO is triggered, although note that user support may not be immediately available, particularly during holidays and weekends. Users are encouraged to be prepared at the start of the semester and generate their observing groups early. See the Phase 2 preparation page for details.

How do I get help?

Help with technical queries (running the exposure time calculator, editing the template proposal form, email submission, etc.) is available from LT Phase 1 Support. Users may also email more general queries to the LT support group, although please refer to the LT webpages first.

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Applying through PATT and JMU

JMU and PATT proposals can now be submitted via our new online interface. Please click on the Proposal Submission link (also visible on the sidebar at left) and follow the instructions. You will need to register an account if you don't have one already. Any queries with this system should be addressed to nrt@ljmu.ac.uk .

PATT Proposal Expiry Policy

Proposals that request time across multiple semesters are usually welcome (see the Call for Proposals for more specific details). However, note that a proposal will expire at the end of the semester, unless time has been specifically allocated in multiple semesters. See the PATT allocations web page for allocations in each semester. If a proposal has not been awarded time in future semesters, you must reapply to facilitate continuation of that project.

Policy for non-JMU PIs applying for JMU-allocated time on the Liverpool Telescope

The ARI Management Board wishes to avoid the situation where teams use JMU staff as "front-PIs" for non-JMU led projects. JMU time may be used to support non-JMU-led proposals, provided they abide by the following rules:

  1. The PI has a strong connection with JMU. This is defined as follows: they are either a former JMU student or member of staff who left the institute less than 1 year ago, or they are a visiting fellow with an agreement which specifically provides for their use of the LT.
  2. The proposal must include at least one active co-I who is currently employed by JMU. This co-I will have good knowledge of the proposal's main scientific area or is otherwise heavily involved in the data reduction and analysis. They will be a co-author on any publication(s) resulting from the LT data obtained.

Note also that no more than 25% of the available JMU time (when there is over-subscription) shall be awarded to non-JMU led proposals.

Southampton and FRODOSpec: The contribution of the University of Southampton to the development of FRODOSpec is recognised as fulfilling the requirement of establishing a strong connection with JMU. Proposals to use FRODOSpec, led by a University of Southampton PI, will therefore be accepted by the JMU TAG (although they are still subject to the 25% rule noted above). Collaboration with LJMU staff as Co-Is is encouraged, but not mandatory. (This policy will be subject to review when the STFC Operations Grant comes up for renewal.)

JMU Proposal Expiry Policy

At the present time, the Expiry Policy outlined above for PATT proposals also applies to JMU proposals.

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Applying through CAT

Applicants for CAT time (PI's based at Spanish institutions) should refer to the procedures at, and download the normal CAT form from, the CAT pages at the IAC.

Applying through CCI

The International Scientific Committee (CCI) of the Roque de los Muchachos (ORM, La Palma) and Teide (OT, Tenerife) observatories regularly invites applications for International Time Programmes (ITP) on telescopes installed at these Observatories. The aim of the programme is to encourage international scientific projects which cannot easily be accommodated for by other time allocation groups, and which foster collaboration between the different user institutions of the La Palma observatories.

Proposals that would benefit from the use of more than one facility, and in particular those which would be unlikely to obtain the large amount of observing time needed to coordinate several telescopes, are especially encouraged. CCI time is only available to PIs from organisations within the signatory countries (Spain, Germany, UK, Italy, France, Belgium and Finland). Proposals should include co-Is from at least three signatory countries, though other co-Is may be from any country.

Applicants for CCI time (international applicants should also consider the Opticon programme below) should refer to the procedures at, and download the normal CCI form from, the CCI page at the IAC (where CCI time is referred to as "5% international time").

Applying through Opticon

Applicants from non-UK and non-Spanish European Institutions may apply for LT time through the OPTICON Trans-national Access programme. Opticon rules state that "the PI and at least half of the Co-Is on the proposal must be working at Institutions from EU member states or EU associated countries that are outside the country which owns the telescope" (in this case, the UK).

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