arXiv:2104.01609v1 [astro-ph.IM] 4 Apr 2021 © .Atohs Astr. Astrophys. J. AstroSat DOI fatooia ore uha trfrigregions, star-forming as such sources astronomical of n251 e.Wt v pcaie ntuet on- instruments specialized five With board, keV. is 2.5-10 sources al., X-ray There in cosmic et of (Ramadevi variability (SSM) monitor respectively. to Monitor 2017a,b) Sky bands Scanning 3-80 keV a the also in 10-150 al., et sensitive and Chattopadhyay are keV 2015) 2017; al., et al., Vadawale et 2016; (Rao Im- X- Telluride (CZTI) Zinc Area Cadmium ager and Large 2017) 2017; al., al., instruments et keV et Agrawal (Antia X-ray 0.3-8 (LAXPC) (SXT) Counter hard the Telescope Proportional ray in The X-ray observes Soft 2016) A band. 2017, al., et bands. (Singh UV near optical, far ca- the is and in observations 2016) simultaneous al., of et pable Subramaniam 2020; instruments. telescope al., (UVIT) et Telescope astronomy (Tandon Imaging Violet X-ray Ultra telescope co-aligned The imaging three UV one and instruments, co-aligned 4 from range energy the min. 98 of ta liueo 5 maoeteErhit circu- 6 a of into inclination Earth the an above at km orbit 650 lar of placed and altitude AM an 10:00 Organisation at at 2015 Research September Space was 28 on It Indian (ISRO) the years. five by last launched the for operational observatory, AstroSat Introduction 1. ninAaeyo Sciences of Academy Indian AstroSat stefis ninmliwvlnt astronomy multi-wavelength Indian first the is 1 usra,M. Hulsurkar, o,J. Roy, 2 ltomcnrlt h oko aaeetof management workflow the to central platform Keywords. functionality. ASSC Abstract. 2015 January 1 accepted 2015; January 1 received MS * eerhOgnsto IR)o 8Spebr21.Atrla After 2015. 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Bhattacharya, , eerhOgnzto IR)adICAhv estab- have IUCAA and (ISRO) Organization Research facilitate to and users of these usage from optimal queries the address di 42 from oig fte aet cuaeyuiiethe utilize already are accurately There to have opportunity. they men- if and scientists training toring, young initiation, the require necessarily India, an would in such available time first is the observatory is this since However, servations. evn ieoe ontoa users. national ob- to the open of ob- time fraction large proposal-driven, serving a a with is mission, It class servatory sources. cosmic from years, data five last the holes, For troSat black dwarf. harbouring white stars, systems neutron from en- emission high and ergy bursts -ray like explosions violent olgswudas eitrse nusing in interested be also and would Universities Colleges in teachers young Moreover, astronomical research. high-quality in- in and them engage Universities and Indian stitutions in researchers and students national front- indigenous art out the carry facility. of state to a country using research the line over of all number large from a scientists to observations opportunity These unique a out. providing carried are been have (TOO) Opportu- of nity Target of observations 239 Moreover, ings. observed ready 1 oadesteerqieet,teIda Space Indian the requirements, these address To eiae nlsssfwr hog osldtdweb consolidated a through software analysis seminates prtos hspprilsrtstevrosapcsof aspects various the illustrates paper This operations. ohfrmkn bevn rpsl n o utilising for and proposals observing making for both , CA,Gnskid ue 1 0,India 007, 411 , Ganeshkhind, UCAA), a enpouigupeeetdhigh-quality unprecedented producing been has bnr otanuesi hs ciiis usahelp a runs activities, these in users train to ebinars etefrAtooyadAtohsc (IUCAA) Astrophysics and Astronomy for Centre AstroSat / nh the unch, ff SO),Bnauu 608 India 560058, Bengaluru, , ) ISRO rn onre.Teei rtclne to need critical a is There countries. erent ∼ AstroSat 20dsic agt in targets distinct 1200 a ueptnilt trc young attract to potential huge has 1 AstroSat hy,P. Bhoye, , r anhdb h ninSpace Indian the by launched ory data. cec upr el(ASSC) Cell Support Science 1 ∼ eagn .C. G. Dewangan, , 39users 1369 AstroSat ∼ AstroSat ,asoftware a C, 10point- 2100 AstroSat AstroSat a al- has As- ob- 1 1 , #### Page 2 of 1 J. Astrophys. Astr. (0000) 000:#### lished the AstroSat Science Support Cell (ASSC)1. The online tools to help users propose for AstroSat ob- cell which is hosted at IUCAA started its operations in servations (explained in details in the next subsection May 2016. With of the AstroSat data made avail- on Software and other resources for proposal writing). able publicly and more such releases expected in the The proposers page provides the pieces of information near future, the role of ASSC is critical in providing the on the upcoming, ongoing and past announcements of science support. We describe the main objectives and opportunities cycles, scientific and technical proposal functionalities of ASSC in assisting Indian and Inter- templates, online tools such as exposure time and visi- national community to participate in observations and bility calculators, simulation and necessary documents using data from AstroSat. such as the proposers’ guide. For data processing and analysis, the latest available pipelines for all four instru- ments are maintained including sample data which al- 2. Functionalities of ASSC lows the user to actually try out the analysis (explained in details in the next subsection of Software and other 2.1 Overview of the web-portal resources for data analysis). The results of the analysis ASSC webpage serves as a web repository of all the of the sample data are made available allowing the new software, latest updates, proposal cycles, publications user to evaluate whether his/her analyses match with and link to various webpages relevant for proposing the standard ones or not. Additional important software with AstroSat and data analysis. ASSC has a central- such as the AstroSat orbit file generator, the Barycentric ized web portal which provides AstroSat users with correction code and the AstroSat Time converter devel- links to tools developed at ISRO, Payload Operation oped in-house at the ASSC are made available through Centres (POC) as well as documents/tools useful for the portal. ASSC has also developed advanced scien- scientific analysis. The Document section in Proposers tific tools such as to compute frequency and energy- page allows user to access the Proposers Guide which dependent time lag from LAXPC data. The ”Recent explains the details of the AstroSat proposal preparation Updates” panel in the right side of the page informs and submission procedure using the APPS software, it all the users about the recent updates and announce- also acts as the proposers’ manual for the APPS soft- ments relevant to AstroSat for example recent software ware. There is a Red Book available in the Document updates, proposal cycle deadlines, health of any instru- section which gives the details of all the accepted AO ment, etc. The home page of the webpage displays all and GT proposals along with the abstract. The Red- the publications based on AstroSat data from all the book helps to check if there is already an observation instruments. Home page also announces the AO cy- proposed or completed for the source of interest that cle opening from time to time as advertised by ISRO. the proposer wants to propose. The home page of the ASSC webpage also displays the picture of the month web portal provides the AstroSat schedule viewer link2 based on AstroSat results which is regularly updated. to check the status of a proposed observation or the planned scheduling of the observations. Further, As- 2.2 Software, webTools and resources troSat handbook is provided to the users explaining the 2.2.1 Software and resources for proposal preparation technical details about the design and characteristics of ASSC provides the software, online/offline tools, doc- each of the payloads on-board the satellite, instrument uments, etc., necessary for the proposal writing. It is calibration, selection of filters, different modes of op- a single platform which contains proposal preparation erations, the primary scientific objectives intended with materials for all the instruments UVIT, SXT, LAXPC, these payloads. The relative angle between the payload and CZTI onboard AstroSat. Using these materials, boresight’s3 (UVIT, SXT, LAXPC) before and after users can simulate energy spectrum, power spectrum, alignment corrections is also available which enables image, etc. They can find the optimum value of ex- the proposer to account for the offset of secondary in- posure time to achieve a scientific goal with AstroSat struments for the proposed observation with the choice observations. As the satellite time is very precious, it of primary instrument. After a successful observation is a crucial step in proposal writing and acceptance of of a proposed target the procedure of the data process- the proposal. These proposal preparation tools are de- ing, data rights, proprietary period, etc. are provided scribed below in more details. in the document ”AstroSat data usage guidelines”. The ASSC web portal maintains up to date information and • AstroSat Visibility: ASSC provides AstroSat visi- bility calculators i.e ASTROVIEWER developed by

1http://AstroSat-ssc.iucaa.in/ 2https://webapps.issdc.gov.in/MCAP/ 3http://AstroSat-ssc.iucaa.in/?q=documents J. Astrophys. Astr. (0000)000:#### Page 3 of 1 ####

ISRO4 and AVIS5 developed by ASSC, which tell ticular signal to noise ratio. If a user provides the the user whether a target of interest will be visible exposure time as input then, in that case, it will to AstroSat for observations during specific peri- give the signal to noise ratio in the output. ods. There may be earth occultation when user wants to observe the source. ASTROVIEWER in- • WEBPIMMS: For observations of X-ray sources, corporates visibility constraints arising from the if a user has prior knowledge of some spectral Sun, the Moon, the Earth and the telescope Ram characteristics of the source with other space- angle in the orbit. AVIS, in addition, also pro- based telescopes like XMM-Newton, Chandra, vides instrument-specific visibility. etc., or with the same telescope AstroSat, the online tool WEBPIMMS11, developed by ASSC • Bright source checking tools: For the safety based on HEASARC tools predicts the observ- of the UVIT detector, it is recommended to able count rates based on the spectral properties check for the presence of bright sources in the providedby the user. This tool can be used for in- Field of View (FOV) which may damage the struments SXT, LAXPC, CZTI and SSM. It uses instrument irrespective of whether these bright some simple inbuilt models. sources are the subject of the proposal or not. ASSC provides link to a tool, called Bright If a user wants to simulate spectrum of a source Source Warning Tool (BSWT)6, developed by with any of the AstroSat instrument, ASSC provides UVIT POC. This tool generates the list of bright two softwares i.e AstroSat.sl and Event Simul, de- visible sources with a magnitude which are near veloped by ASSC, for spectral and temporal data re- the proposed position. It also mentions that spectively. For UVIT, ASSC also provides a tool whether any source is too bright to observe or UVIT simulator, developed by UVIT POC, to sim- not and which filter is not safe for the observa- ulate image. All these software tools can be found at tion. This tool tells about the safety of UVIT the section ”downloadable resources” of the webpage filter based on the modelling from visible mag- ”proposal preparation”12. nitude. There are other tools to check the safety of VIS and FUV/NUV channels of UVIT sep- • Spectral simulation code AstroSat.sl: An ISIS arately. UVIT VIS filter checking tool code AstroSat.sl, can be used to simulate the (Theia)7 is used for VIS filter whereas a energy spectrum using any model. It is a single tool UVIT FUV/NUV filter checking tool code which can work for all instruments UVIT, ()8 is used for FUV and NUV filters. SXT, LAXPC and CZTI. Users can get the ex- Both are developed by UVIT POC. ASSC pected count rate for input spectral parameters also provides a UVIT 9-point coordinate for all the instruments. However, a user can take generator script, developed by ASSC itself. response files from this place and perform the This tool generates 9 points around the proposed simulation on another platform like XSPEC, etc. source to quickly scan the area around the pro- also. posed target. This is essential for those fields for which prior UV observations do not exist. • Timing simulation code Event Simul: For the simulation of temporal properties like lightcurve, • Exposure Time Calculator for UVIT instru- power spectrum, detection of quasi-periodic os- ment: ASSC provides two separate online tools cillations (QPOs), etc., ASSC provides a simula- i.e , UVIT exposure time calculator at tion code Event Simul. It works forthe LAXPC IIA9 and UVIT exposure time calculator instrument. at Calgary (Leahy et al., 2014) 10, to estimate the exposure time. This tool calculates the ex- • UVIT Image simulation code: An image simula- posure time by taking source characteristics as tion code, UVIT simulator to simulate the im- input. It gives the exposure time to achieve a par- age of the source. In this software, a user pro- vides the image of the same source with other telescopes and some parameters like exposure ff 4https://webapps.issdc.gov.in/astroviewer/jsp/UserInput.jsp time, size of the field of view in arcsec, e ective 5http://AstroSat-ssc.iucaa.in:8080/AstroVisCal/ area of UVIT detector, etc. as input. 6https://uvit.iiap.res.in/Software/bswt 7http://uvit.iiap.res.in/Software/theia/ 8http://uvit.iiap.res.in/Software/gaia/ 11http://AstroSat-ssc.iucaa.in:8080/WebPIMMS ASTRO/index.jsp 9https://uvit.iiap.res.in/Software/etc 12http://AstroSat-ssc.iucaa.in/?q=proposal preparation 10http://uvit.ras.ucalgary.ca/cgi-bin/UVIT.cgi #### Page 4 of 1 J. Astrophys. Astr. (0000) 000:####

Finally, a user can prepare a proposal using the (like Julian date, modified Julian date, etc.) and vice tools mentioned above. The user needs to prepare versa is also available here17. the proposals using scientific justification and technical Documents related to the installation of justification templates and submit the proposal through pipeline software and analysis procedure are ei- the AstroSat Proposal Processing System (APPS). ther attached with the software or separately available. As for UVIT data analysis, two doc- 2.2.2 Software and resources for data analysis Since uments UVIT Pipeline Cookbook v5.pdf and photons from an astronomical source can interact with UL2P quick installation and output product the instrument, background photons can also reach on help v9.pdf18 can be used to understand the pro- the detector. We should have some procedure to dif- cedure. At the same time, the SXT pipeline guide is ferentiate between source′s genuine feature and un- attached to the pipeline software. For LAXPC data wanted signals. We also need some methods to convert analysis software LAXPCSOFT, readme files for all the observational data into a particular format, which the tasks are attached to the software. A user can can be used to generate spectra, images, etc. For this follow these files to understand the analysis. For the purpose, ASSC brings necessary software tools like CZTI, ASSC provides the user guide for the same. pipeline software, calibration files, etc., from the re- spective POC of instruments. It also develops some 2.3 APPS tools. It also has some data analysis tools. The ASSC APPS19 is an online webpage assisting scientists in web-portal makes available these tools and related doc- proposal preparation, submission, scientific and techni- uments. All these materials can be found on the web- cal review and selection process. APPS caters to dif- page ”Data & Analysis”13. ASSC team updates the ma- ferent types of users including the General or Guest terials from time to time. There are three software that Observers, Payload Operation Centre team members, can be used to analyze LAXPC data. payload scientists and proposal reviewers. APPS is • LAXPCsoftware FORMAT A software to do all deployed at the Indian Space Science Data Centre tasks separately. (ISSDC), ISRO, . APPS has been success- fully used for proposal preparation, submission and se- • laxpc soft FORMAT B software to do all tasks lection for observations in the (i) performance verifi- in one step. cation (PV) phase in the first six months of AstroSat operations, (ii) six Guaranteed Time (GT) cycles, (iii) • LAXPC Level 2 Data Pipeline Ver 3.1 is another ten Announcement of Opportunity (AO) Cycles, Target package to analyse LAXPC data. of Opportunity proposals, Calibration proposals, and LAXPC gain record and HV record are also updated Legacy proposals. Details of the APPS is provided in regularly. For SXT data analysis, other than pipeline (Balamurugan et al., 2020) of this issue. Over the last software, ASSC provides software to merge orbit wise five years, the ASSC at IUCAA has played a crucial event files and to generate the ancillary response file role in fixing of bugs and security issues, documen- (ARF) file formation 14. These software are also devel- tation, and feature enhancements. They have visited oped by SXT POC. ISSDC, Bangalore and coordinated with the ISRO team ASSC also provides a higher-level resource for data to make APPS software secure and on managing re- analysis. A software COMPT-Time-Lag-RMS, devel- sources and memory leakage in APPS software. oped by ASSC, is used to study the dependence be- tween spectral and temporal properties. It can com- 2.4 AstroSat Helpdesk and Visitor Programmes pute the energy-dependent time lag when seed photon The ASSC team at IUCAA manages AstroSat temperature is varied or coronal heating rate is varied. helpdesk20 to address a large number of queries from Other than this, ASSC provides an online tool to gen- AstroSat users on proposal preparation, software instal- erate an orbit file15 which is useful in the barycentre lation and usage and data analysis. These queries are correction. Software related to the barycentre correc- based on the issues faced by the proposers in procuring tion (as1bary) is also provided 16. An online tool for data based on the announcementof opportunity and tar- the conversion between AstroSat time and other time get of opportunity observation cycles, issues related to

13 // / = http: AstroSat-ssc.iucaa.in ?q data and analysis 17http://AstroSat-ssc.iucaa.in:8080/AstroSattime/ 14 // / = http: AstroSat-ssc.iucaa.in ?q sxtData 18http://AstroSat-ssc.iucaa.in/?q=uvitData 15 // / / http: AstroSat-ssc.iucaa.in:8080 orbitgen 19https://apps.issdc.gov.in/apps/auth/login.jsp 16 // / = http: AstroSat-ssc.iucaa.in ?q data and analysis [email protected] J. Astrophys. Astr. (0000)000:#### Page 5 of 1 ####

software installation and analysis procedure, address- the time allocating committee and the Science Working ing software related bugs. Helpdesk re-directs the more group are also organized by the ASSC. involved inquires to the respective Payload operation centres. AstroSat helpdesk facilitates the Indian and in- 2.6 Resources relevant to publication and calibration ternational proposers with proposal based queries and The calibration webpage of ASSC website provides ensures smooth proposal submission during the pro- the list of calibration sources observed by the AstroSat posal cycles announced at regular intervals from ISRO. satellite. The list mentions the effective exposure of Some of the queries which are generic to all the users each of the observation instrument wise. It is highly are listed in the frequently asked questions (FAQ21) list beneficial for the user to use this data for calibration available at ASSC webpage. purposes. Some of these datasets are open access and In the last 4 years, the ASSC hosted more than ∼300 some proprietary of the proposer or the instrument visits by Ph.D students, University and College teach- teams. This page also provides the list of publications ers, as well as a few experts who interacted with the based on calibration and performance of the payloads ASSC staff and used its facility. Help was provided onboard the AstroSat satellite. to these visitors, who came from different parts of the country, to analyze the data they had from their own With a lot of the AstroSat data being released to the proposals or given to them. public and more such releases expected in the near fu- ture, the ASSC will be critical in providing the oppor- 2.5 Workshops and Meetings organized by ASSC tunity and means for the larger scientific community to ASSC organizes national workshops and meetings in take part in optimal utilization of AstroSat data. various locations across India since July 2016. These workshops were a set of extensive demonstration ses- sions where the participants were instructed on how Acknowledgements to propose for AstroSat observations, in particular the choice of how to configure each instrument, exposure ASSC team would like to thank AstroSat mission of the times, filters etc., in order to optimize the Science out- Indian Space Research Organisation (ISRO), the Indian put. Proposal writing techniques, simulation of ex- Space Science Data Centre (ISSDC) team. We thank all pected science results were explained. Other than the the instruments POC teams for their support for solv- scientific and technical justification details and types ing queries and time to time help with new software of proposals to be sought for during an announced cy- updates. cle, these workshops focus on hands-on-training ses- sions of data analysis techniques of different instrument References onboard AstroSat. The content of the webinars and a few talks are also available in the web-portal. ASSC Balamurugan, C., et al. 2020, JAA, This Volume also conducts refresher course in Astronomy and Astro- Tandon, S. N., Postma, J., Joseph, P.et al. 2020, ApJ, Volume physics for teachers at Indian universities and colleges 159, Issue 4, id.158 for observational and theoretical aspects of astronomy Subramaniam, A., Tandon, S. N., Hutchings, J. B. et al. and state-of-the-art methods of data analysis, especially 2016, SPIE, 99051F with AstroSat. ASSC trained more than 489 partici- pants to enable them to propose with AstroSat and to Leahy, D., 2014, Astronomical Data Analysis Software and handle data analysis of AstroSat during its 4 years of Systems XXIII. Proceedings of a meeting held 29 Septem- existence. A Workshop was conducted where experts ber - 3 October 2013 at Waikoloa Beach Marriott, Hawaii, guided M.Sc/M. Phil students to analyze and interpret USA. Edited by N. Manset and P. Forshay ASP conference AstroSat data, which directly led to the publication of series, 485, 69 the results with the students as co-authors Mudambi et Singh, K. P., Stewart, G. C., Westergaard, N. J. et al. 2017, al. 2020 and Jithesh et al. 2019. Details of completed JOAA, 38:29 and upcoming workshops are regularly updated in Singh Kulinder Pal, Stewart Gordon C., Chandra Sunil et al. the webpage http://astrosat-ssc.iucaa.in/?q=workshops. 2016, Proc. SPIE , Volume 9905, id. 99051E pp. The distribution of participants’ affliations and loca- Antia, H. M., Yadav, J. S., Agrawal, P. C. et al. 2017, ApJS, tion of the workshops organized by ASSC is shown in 231:10 (29pp) Figure 1. AstroSat related meetings such as those of Agrawal, P. C., Yadav, J. S., Antia, H. M. et al. 2017, JOAA, 38:30 21http://AstroSat-ssc.iucaa.in/?q=faq #### Page 6 of 1 J. Astrophys. Astr. (0000) 000:####

(a) (b)

IUCAA : 23% Institute Students : 38.62%

College Students : 17.65%

Online : 8%

Outside IUCAA : 69%

University Students : 43.73%

Figure 1. Pie chart (a) shows the distribution of participants affliations of undergraduate colleges affiliated to universities, universities and research institutions, (b) presents the locations of different workshops organized by ASSC.

Rao, A. R., Bhattacharya, D., Bhalerao, V. B. et al. 2017, Current Science, Volume 113, Nr 4, 595, Chattopadhyay, T., Vadawale, S. V., Rao, A. R. et al. 2016, Proc. SPIE 9905, Space Telescopes and Instrumentation 2016: to Gamma Ray, 99054D Vadawale, S. V., Chattopadhyay, T., Rao, A. R. et al. 2015, A&A, 578, A73 Ramadevi, M. C., Ravishankar, B. T., Sitaramamurthy, N. et al. 2017a, JOAA, 38:32 Ramadevi, M. C., Seetha, S., Bhattacharya, D. et al. 2017b, EXP ., 44:11–23 Jithesh, V., Maqbool Bari, Misra Ranjeev et al. 2019, The Astrophysical Journal, Volume 887, Number 1 Mudambi Sneha Prakash, Maqbool Bari, Misra Ranjeev et al. 2020, The Astrophysical Journal Letters, Volume 889, Number 1