Thai National Telescope Call for Observing Proposals Cycle 2: November 2014-April 2015

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1 Thai National Telescope Call for Observing Proposals Cycle 2: November 2014-April 2015 Due Date: August 17, 2014 Proposals are invited to request time on the 2.4m Thai National Telescope (TNT) for the Cycle 2 season, beginning November 1 st 2014 and ending April 30 th, Also in this second Cycle several commissioning activities are foreseen, in particular concerning the two new facility instruments MRES for spectroscopy and 4K ARC for imaging. As before, eligible proposers will be restricted to researchers affiliated to Thai institutes, and researchers from institutes holding special Agreements with NARIT. The proposers should read carefully the special terms and follow the instructions. The proposal form should be duly filled and submitted by to proposal@narit.or.th Proposals received after August 17, 2014 (midnight Bangkok time) shall not be considered. The Proposals will be reviewed and ranked on the basis of their scientific merit by a Time Allocation Committee (TAC) nominated by the NARIT Director. TAC members include qualified researchers from NARIT and other institutes in Thailand and Asia, and are rotated on a biannual basis. A technical feasibility review by the NARIT Operations Department will further screen the proposals. Applicants will be notified of the outcome of their proposals by October 1 st, Observers are expected to contact the NARIT staff to prepare their visit at least one month in advance of their run, and to cover their expenses for travel to the TNT Doi Inthanon site and for local accomodation and subsistence. A set of Instructions for Visiting Astronomers are available to facilitate the logistics of the visit. Visitors are strictly required to fill an End of Run report and submit it to the NARIT staff within one week after the end of observations.

2 IMPORTANT NOTICE: Special Terms for Cycle 2 The TNT is fully functional but several technical activities are still in progress, among others: the Telescope Control Software is being extended in functionality and subject to tests; some instruments (e.g., MRES and the 4K ARC camera) are ready but not yet tested on sky at the time of writing; the autoguider has not yet been commissioned and characterized; the data archive is under development. As a result, it is anticipated that some interruptions, changes and delays might affect the allocated observing runs. Also note that as a public organization NARIT is committed to allow visits by members of the general public and by small groups. Although every effort is made to schedule such visits to have the least impact on scientific observations, a few last minute problems might be unavoidable. Observers will be informed ahead of time as much as possible. Proposers are kindly asked to acknowledge the situation and to accept that observations in Cycle 2 will be carried out on shared-risk basis. IMPORTANT NOTICE: Authorship Acoording to the Memorandum of Understanding between NARIT and the ULTRASPEC Consortium, all papers based on observations carried out with ULTRASPEC at TNT during Cycle 1 and Cycle 2 (i.e., until April 2015) shall include at least Professors Vik Dhillon and Tom Marsh from the ULTRASPEC team.

3 INSTRUCTIONS Proposers are required to read carefully this section before preparing their requests. 1. The Telescope and Observation Planning The telescope is an alt-az with 2.4m primary mirror 1 and two f/10 Nasmyth foci. At present, only one of these is equipped with a derotator. An autoguider is present but not yet fully commissioned. It should be available during Cycle 2. Without the autoguider, the current tracking performance is sufficient to guarantee subarcsecond performance over about 15 minutes, depending on elevation. The TNO site has a distinctive tall telecommunications tower to the East of the telescope, which blocks observations in a restricted area of the sky. Requesters might consult the observing horizon map while preparing their observations. Requesters are advised to check carefully the observability of their targets depending on coordinates and time of the year, i.e. using a tool such as Staralt, which already includes the TNO site. The telescope can point to very low elevations, however starting from about 30 degrees elevation the dome introduces some vignetting. 2. The Instruments In Cycle 1, the following instruments will be available: ARC 4k camera. This is the facility imager for all science goals not requiring time resolution shorter than ~100s (where ULTRASPEC is the most suitable instrument). The camera has been designed and realized by ARC (Astronomical Research Cameras, Inc.), and is based on an E2V thinned, astronomy broadband AR coated, Grade One CCD with 4096 x 4096 x 15.0 micron pixels. The field of view is 8 on the side and the RON is 4e-. The camera is equipped with UBVRI, Hα, red continuum, and *SII+ filters. The camera s control software and data reduction pipeline are being developed and/or commissioned in Cycle 2; basic calibration of imaging product will be delivered on a best-effort basis. ULTRASPEC, a visitor instrument delivered under a Memorandum of Understanding among NARIT, the University of Sheffield and the University of Warwick (PI V. Dhillon). Born out of the experience with the successful ULTRACAM fast 3-band camera and using similar acquisition electronics, ULTRASPEC is based on a state-of-the-art low-light level (L3) Electron Multiplying CCD by e2v with 1k x 1k x 13µm pixels with virtually zero RON. One key feature is the so-called frame-transfer, which enables fast data readout (100ms full frame, and up to 10ms on subarrays). ULTRASPEC is ideally suited to measure fast varying phenomena such as flares, 1 The primary is currently masked to 2.3m clear aperture, to avoid diffraction from the mirror edges.

4 outbursts, transits, etc. It has been widely used already in Cycle 1. The ULTRASPEC consortium has a right to Guaranteed Time Observations, but open time is also available for other requesters. MRES, a medium spectral resolution (R=15,000, 1.4 slit; 2 pixel resolution R=17,000) fiber-fed echelle-spectrometer manufactured by Nanjing Institute of Astronomical Optics and Technology(NIAOT), China. It is based on white pupil optics design with R2.6, g/mm, blazed at 69 degree echelle and covers the nm spectral range with an Andor 2048x pixel size CCD. The instrument will be installed and commissioned just before the start of Cycle 2. Therefore, performance and reliability are not yet guaranteed. Meaburn Spectrograph, a low-resolution fibre-fed spectrograph (R 650, 50μm dia. fibre) designed and manufactured by Prof. John Meaburn, and decommissioned from the 2.0-m Liverpool Telescope. It is based on white pupil optics design with reflection grating, rotatable by a driving motor to select different spectral ranges. The version in use at NARIT has been slightly modified from its original state. The fibre-fed system is now a single 50μm fibre instead of the original bundle of 50x50 μm fibre. The current setup can take the full optical spectrum coverage (3900A-8000A) in 3 grating settings each cover approximately 1500A. It has also been upgraded to use the QSI 632 CCD camera (2184x x6.8μm pixels, RON=7e- RMS, -25C) which can be TE cooled down to -20 to -25 C. At the time of writing, we have received on loan from Prof. Qian Shenbang s group (Yunnan Observatory) an Andor ikon-l CCD camera (2048x x13.5μm pixels) with 2.9e- RON RMS and negligible dark current. eshel, a commercial echelle spectrograph from the Shelyak manufacturer, operating in the nm range with ~10,000 spectral resolution. It is based on a QSI632, 2184x1472 pixels, 6.8x6.8 micron CCD. It is fiber-fed, but given the long focal length of the telescope the fiber core size is not ideally matched to the image size. As a result, the efficiency is relatively low. Users interested in this level of spectroscopic resolution should request MRES. Eshel will be used only in case of problems with this latter. Important note about spectroscopy: all three above mentioned instruments are available and can be requested. However, as MRES has not yet been received, the actual implementation aspects and change-over procedures from one instrument to another have not yet been defined and tested. Requesters should keep in mind that priority will be given to MRES, and in case of conflicts the NARIT OPD will contact the proposers. 3. Performance An Exposure Time Calculator (ETC) is available for ULTRASPEC, from V.Dhillon s web page.

5 For spectroscopy, an ETC is not yet available. As a guideline, the estimated sensitivity limit of eshel at TNO is V=11 in 30 minutes for 0.9 star images (courtesy of Dr. Mkrtichian); the sensitivity of MRES will be measured in October-November Concerning the Meaburn Spectrograph, the size of the fibre on the focal plane of the f/10 TNT is about 0.4, introducing an unacceptable light loss for a typical seeing of The problem is somewhat lessened by using the focal reducer f/10 to f/3.3 which increases the size of fibre on the sky to about 1.2. The current magnitude limit (based on 45min-60min integration time) for point sources is around 13-15mag, depending on the seeing conditions. The magnitude limit will be improved with the pending upgrade of the detector. Also, the following overheads should be considered in the time requests: Telescope pointing and acquisition: 5 min Filter changes: 30s Flat-Field, Dark: usually included in the calibrations at the beginning and end of night. Other calibrations: consult the NARIT staff Concerning imaging, please note that the current combination of baffle and telescope optics results in a straylight excess which is approximately circular in shape and peaking to about 5% of the background at the center of the field. The actual straylight distribution might depend on factors such as elevation and lunar phase, and might be difficult to remove. A new baffle system is under realization and should be available in Cycle Weather The weather at the Doi Inthanon site is known to have not only a large seasonal variation, but also significant fluctuations of conditions from one night to the next and within the same night. In particular, humidity can vary from extremely dry in some winter nights (below 10% RH), to condensing conditions even when the sky is clear. A set of rules to open and close the dome are in place and will be followed by the Telescope Operator in charge. Weather statistics are still incomplete and therefore for this Call it is recommended that requesters apply only for the time strictly needed for their observations, without allowance for weather factors. Similary, the seeing conditions are not yet fully characterized. Experience in Cycle 1 has shown that the seeing can be as good as 0.8, it is often around 1.2 and is generally better than 2. About 75% of the nights were classified as usable (telescope open at least part of the night).

6 CONTACTS Action Notes Proposal submission: Deadline August 17, 2014 Inquiries about travel and accomodation arrangements: Inquiries about Instrumentation availability and performance: End of Run report: