Joint Science Discussions with XRT and SOT.#19th March 09:00
This page refers to one day of a closed meeting of the EIS consortium
Comments from attendees welcome!#If you are attending this day of the meeting, please comment here if you would like to give input.
Those without an EISWiki account (shame on you... if you're on the team!) can mail their comments and intended contribution topics to David Williams.
It would be good to have a discussion about this agenda before the meeting, here on the EISWiki.
Format#At this meeting, there will be additional attendance by invitees from XRT and SOT.
Objective#What did we discover were thorny science questions in the EIS Science session?
The main point of this day session is to construct some observing programmes to conquer(!?) these questions using information from the EIS, SOT and XRT participants at this meeting.
SOT & XRT Primers#Most people attending this session will be familiar with the kind of physics that the post-launch EIS offers information on. So we thought it would be useful to have a primer on each of the other two instruments’ scientific capabilities, with the benefit of 2.5 years of experience.
XRT (Kelly Korreck)#
XRT#XRT do have quasi-standard Flare mode is operational the Automatic region selection: can read the patrol images which are interleaved.
Takes about a day to create a new programme. QL images are available within a day. Would want people to check those images L0 data takes about a week to be
PRY: do the QL images go on the web? KK: Not sure, but don't think so. Maybe they could.
- Data availability
KPD: is there an explanation of XRT_CAT KK: XAG.pdf is in SSW and on the SAO webpage. Also have a file from the Paris workshop to show how
HEM: is it updated a lot? KK: XRT_PREP is, but the analysis process isn't much different. HEM: but the analysis guide KK: There is someone tasked with providing the new version of the filter ratio programmes.
READ_XRT creates SSW-style index-data pairs. Then run XRT_PREP on that. There's been a lot of work on that. Documentation is in the IDL software headers.
- Temperature analysis
JI: is there a synoptic daily temperature map? KK: Not yet. Maybe Narukage has the way to do that.
- Effects on-orbit
- From Dec 2006 to Jan 2007, don't trust the header information: it's all Al_Poly.
- absorption layer is decreasing response (make_xrt_wave_resp). This is a time-dependent absorption function. So it's a fairly sticky bit of correction. There was a hope of coming up with a photometric correction. There's nothing in the software
- spot-like contamination -- can remove this with xrt_tup_comtam. This does a simple averaging. Another to be released soon does gradient fits iteratively. The attenuation isn't 100%, though, so you can recover the contrast in those areas in many cases, with AR signal levels.
- cross-calibration with EIS, etc. May be a bone of contention?
TWo lists can be joined: xrt_science -- discussion of science xrt_users -- for end-users to provide support for one another.
KPD: one of the things I'd like to have are movies or time-sequences from a single filter or single exposure times. Can you make them with XRT_CAT? KK: There's no standard EDL: XRT_CAT, WHERE on filter wheel.
- Sheared field in ARs through morphology.
- DEM intro:
- Flare shrinking loops through morphology
- Sigmoid structures
- Polar jets: XRT are interested in getting densities out of them.
- CMEs See dimmings in XRT. If EIS were pointed at the same place.
- outflows: SO much easier to find in EIS than in XRT. Great use of EIS.
- Sheared loops within filament channels.
- Coronal waves
-- What have we learned to do to improve observations. Every time we want to look at the high-T plasma, we should have a programme where we know what XRT, EIS and SOT are doing.
SOT (Tom Berger)#
- BFI Characteristics is a great slide -- it explained a lot of the physics SOT was intended for.
Spatial resolution shows magnetic elements with res down to 150 km. Not as good as some ground-based, but SOT gets this continually, rather than once or twice a year.
Spatial stability is good to about 0.01 arcsec RMS. CT works at around 840 Hz!
Focus stabiilty of the telescope -- telescope is continually shrinking so focus is changing but hasn't yet stabilised.
Focus stability during eclipse season isn't very good: you have a sort of 10-step shift. If you need absolute highest resolution, do it outside eclipse season.
EDL: Do you use a thicker slit in eclipse season? TB: No - same slit.
You're not completely out of focus and can't see granulation, but you can still see the magnetic elements.
There is chromatic aberration - when you want to request NFI and SP, say which is your *primary* one. The things I'm saying about resolution are non-summed. But if you sum on the camera, 2x2, then the defocus is much less important. Especially in the Ca II, this is quite common.
BFI Filter throughput decrease: The loss isn't that great and can just increase the exposure time.
SOT NFI is down to 40 or so percent for Fe I 6302.5, but Na I D magnetograms at 589 are unaffected due to the other coating.
Current situation is that there is NO bubble in the NFI. And so we can now tune the filter back and forth!!
- 8 seconds or so to tune between lines. THe maximum cadence is about 8 seconds between
Karin: I used to see fringes TB: Yeah, but now the flat-fields take it out.
September-October and February-March are when the orbital Doppler shifts are minimal, so optimal for Dopplergram velocity.
EVen from relatively wimpish flux emergence in SOT, you can see very bright points in the corona with XRT.
Shine or Berger can do cork-maps to do LCT on granules and get a horizontal velocity field.
SST with the same analaysis... with a 1m telescope, you can get a mich higher resolution with much more regularity.
Ca II H at the limb: 1.6 second cadence. We believe we are now capturing the dynamics in spicules! Including what appear to be rotational motions.
They have standard data products for off-limb prominences H-alpha dopplergrams, too.
Full SP takes about 3 hours in most sensitive 'normal' mode. Doesn't have the resolution of the FG: about a factor 2 worse. FG suffers from Zeeman saturation when the spectral line moves out of the passband of the FG. But in the SP, this doesn't happen and you do get accurate data.
In L2 total polarisation maps, you can sometimes see very weak, fuzzy emission which indicates horizontal field emerging! Very sensitive.
Lites: No crosstalk between I,Q,U & V -- this is the BEST calibrated polarisation instrument known.
Planning: new calendar on Google:
email@example.com calendar is editable by some people. PWD hatsuhinode lets you see it. Different HOPs have different colours. There are also calendars for instrument events. Have scheduled in the meetings.
Give it a try!
KPD: do you have any problems with pointing or keeping on a target in eclipse season? It doesn't look like it. TB: It's enough so that if you were to try to overlay a raw SOT images onto an XRT image, it would be offset. Shimizu-san has made a database online which allows correction of that to about 5 arcsec. KPD: so outside eclipse season we should be able to do this quite well DHB: there is a drift between SOT and EIS: what is that? TB: That's the correlation tracker at work, and getting all the information together to work that out is challenging. EDL: Do the data exist to complement the cork studies? TB: would be good to ask Shine if he wants to go up higher into the atmosphere.
Karin: You can take out the slit motions in Y but how about in X? TB: Actually this is only happening after the slit, on the Littrow, so it can't change the X position of the slit.
EDL: the magnetic (prominence) bubbles - is it the MHD, HD? TB: BC Low believes it's a solenoidal knot field emerging and then rising up into the equilibrium of the cavity. I'm convinced it's also thermal, that it's hotter. Neal Hurlburt is now simulating this as a concentrated field and it doesn't rise unless he heats if first. EDL: it looks like a radiative interface. TB: Yes, it's a plasma pile-up I think, cos you see the plasma falling down and stopping on the rim. It's one of the main goals of the SUMER campaign in April. Karin: how large TB: about 50 Mm, and they live for an hour or more, so we'd have to get very lucky, to scan SUMER across it. Could get readings in TR lines. If it's a purely thermal effect, the speed of the rise indicates a certain temperature rise.
What was SOT looking at...?#Knowledgebase
If you have a particular date in mind, it's very easy.
SunGate portal looks like just the thing we were talking about yesterday.
Because a lot of the SOT datasets are very large. So rather than reading it all into memory, you can tell it to read in a filelist, then dump the output to disk.
SP: L0 is the raw reformatted 4D data. Mostly just reading one side of the CCD now.
http://sot.lmsal.com/data/sot/level1d means you never have to run SP_PREP(!). Just go there for SP data.
KPD: what's the noise level in these data? TB: 2 - 5 gauss.
For QS, we can now tel you the QS field with rapid scans across a small area 10x164" would take just minutes, depending on sensitivity. Can also shorten the slit if necessary.
SOME level 2 data are online at http://sot.lmsal.com/data/sot/level2 - they are calibrated IN GAUSS.
Can take these data and make a vector field if you want.
Lastly, I note that we have the SOT analysis guide and it includes the Paris Tutorials on certain datasets, including SP_PREP if the data centre each
Bruce probably has a tool he can give you to get Bx, By, Bz. EDL: notwithstanding the 180º issue. TB: MERLIN code has KPD: the inclination is to the LS
Addressing Our Major Science Goals#Discussion Session Having talked about 1. the science issues we think are outstanding for EIS, (previous day) 2. what SOT and XRT can offer in terms of physical observations, we need to marry these and work out what co-observations we all want in order to address our major science goals.
- HEM would be interested to put together a joint EIS XRT temperature distribution. (XRT: Reeves, Narukage; EIS: Warren, Mason)
- LKH thinks there’s a disconnect between horizontal magnetic fields o EIS could potentially do something there WHADDAYA WANT?
XRT: Paolo Grigis; EIS: Karin Muglach
* GAD: SOT discovered spicular material that‘s moving at very high velocity Type I and II I ordinary: II straws: Look for events in EIS and XRT that overlap with SOT discoveries: look for the most dynamic stuff in EIS. Trigger is an SOT event. Take emerging flux, etc., and ..... look in EIS & XRT data for response. Spicules -- disappearance of the H-alpha spicules: is it thermal? can we measure where that happens? Need to consider the dynamical timescales, observed off-limb. TJW: SUMER has observations in Si III (SOT: Bart de Pontieu; EIS: Hansteen; ) ISSI Meeting in Jan had this as a major topic. Lingangan ApJ 679 L167 good place to look up, too. ---
* JTM we have great difficulty at getting quantitative information o JLC is the filter ratio method working quantitatvely + think the XRT filter ratio people have confidence, but when you compare that with EIS o JTM: I just want to know where the hot plasma is o JLC: if you see it at all in XRT, it‘s hot, but that‘s qualitative o HPW in principle should be able to put these things together. We w
If you want to look at hot structure, DEM aside, Narukage. More general point, disappearing filaments: are they heated, if so how? Simple filter ratios enough. What happens in EIS and XRT when photospheric features vanish/change. 14th Mar 09: XRT sees post-eruption loops (see XRT POW page on main webpage.) (XRT: Narukage & for filament disappearance, Y Su; SOT: H-alpha & B field, Berger; EIS: JLC, Green, Tripathi)
* LKH: Outflow areas: what does Ca II H look like? EIS: Young, Doschek, Harra; XRT: Korreck, SOT: Berger – see HOP 96 H-alpha vels on disc, blocking filter band is shifted, so you get contin contamination and unreliable vel's. But off-limb okay. Near limb AR might be okay, with SOT looking just off limb at the chromosphere. Most of the data applicable would be prominence observations.
* HPW: could SOT provide a measure of the vector magnetic field Any updates on Karel S. does with extrapolations? Not since Boulder.
* HPW: think we should do what Helen has done and get cross-calibrated joint observations
* HEM: cores of active regions: high temperatures. XRT: highly transient structures rule out multi-filter observations. AEC defeats you, so... one filter has a greater chance of working. Looks like the distinct discussion groups need to be integrated. XRT: Grigis, Korreck, McCaughey; EIS: Mason, Ugarte; SOT: Tarbell). XRT would now do single-filter at high cadence, with a filter that's moderately thick. TJW: SUMER sit'n'stare; at loop top, it may be worth plonking EIS there to look for slow-mode oscillations at high T in flaring loops.
EDL: Diagnostics from the slots? Density diag's could be feasible. The jets' thermal structure, can it be derived? But density useful, too, because of the ionisation balance range. LKH: It may also be possible to derive velocities, too. (EIS: Sun, Harra; XRT: Savcheva, DeLuca; SOT: Look to get EIS to look at one set of parameters and XRT to look at its main strengths. SP Scans at south pole show good signal (exp. time unsure); DHB: H-alpha at the poles?;
- TB: Coronal cavities; S. Gibson & D. Schmidt, multi-day campaign was run: needs an EIS mentor: EIS: Tripathi; no SOT component, nothing much to see ≥30" above limb.
- Prominence bubbles (HOP 73):
If the bubbles are intermittent, they should be on the disc, too. Look at filaments for intermittent velocity events. May not be able to see the upflows directly with SOT, but it might be possible with EIS.
How to prioritise the requests about Active Regions, Flares, etc.
Use the flare flags, Be_Thin to control saturation...
T.Sh.: Strong TLM constraints, but a v. important target. Want more widely applicable studies, in terms of the number of science questions you could address. Last Sep's SWG tasked small groups to discuss the most suitable observing programmes for ARs and Flares. There are 6 or 7 standard sequences suitable for B field evolution in ARs; as well as for major flares. (for SOT, this is). But for EIS, XRT... We're typically operating as an observatory, responding to multifarious requests. When we've an AR, there are many conflicts between these and core programme desires. Energetic ARs may trigger another observing mode, where we concentrate on this kind of target. Need several standard programmes.
EDL: Had to demonstrate the XRT could respond to the flare flag in a timely manner. Demonstrated now. DHB: will probably test the EIS internal flare flag, too. Maybe triggering off He II first.
HPW will forward what we have so far to the EIS team.
Good to announce this mode first so that people are aware of the sensitivity to busy active regions.
- Tom Berger
- Additional input from Bruce Lites (not attending)
- Jack Ireland
- Ted Tarbell (unable to attend)
- Alex Young
- Tom Berger
- Ed DeLuca
- Kelly Korreck
Topics#These will be an output from the previous day's EIS Team Science Meeting.
- Khalid al-Janabi (MSSL)
- Danielle Bewsher (RAL)
- David Brooks (NRL)
- Charlie Brown (NRL)
- Paul Bryans (NRL)
- Len Culhane (MSSL)
- Ken Dere (GMU)
- George Doschek (US PI; NRL)
- Alessandro Gardini (UiO)
- Hirohisa Hara (NAOJ)
- Louise Harra (PI; MSSL)
- Shinsuke Imada (NAOJ)
- John Mariska (NRL)
- Helen Mason (DAMTP)
- Keiichi Matsuzaki (ISAS)
- Ryan Milligan (GSFC)
- Karin Muglach (NRL)
- Steve Myers (NRL)
- John Rainnie (RAL)
- Toshifumi Shimizu (ISAS)
- Ignacio Ugarte Urra (NRL)
- Harry Warren (NRL)
- Tetsuya Watanabe (Japan PI; NAOJ)
- David Williams (MSSL)
- Peter Young (NRL)