This page (revision-828) was last changed on 03-Feb-2017 10:35 by Denver

This page was created on 04-Feb-2009 11:25 by David R Williams

Only authorized users are allowed to rename pages.

Only authorized users are allowed to delete pages.

Page revision history

Version Date Modified Size Author Changes ... Change note
828 03-Feb-2017 10:35 18 KB Denver to previous The line's engaged cena anafranilu Minter is now trying his hand at headhunting

Page References

Incoming links Outgoing links
TeamXRTSOTJointMeetingMar09
TeamXRTSOTJointMeetingMar09

Version management

Difference between version and

At line 1 added 2 lines
[{ALLOW edit EISMainUsers}]
[{ALLOW view Anonymous}]
At line 97 added one line
some people didn't know how big the EIS slit was and in general people didn't know what to ask for for morphology studies. ''maybe that cadence isn't the primary factor, then -- work on informing people about spatial coverage in a given time frame''.
At line 99 added one line
* Polar jets: XRT are interested in getting densities out of them.
At line 101 added one line
* CMEs See dimmings in XRT. If EIS were pointed at the same place.
At line 103 added one line
*outflows: SO much easier to find in EIS than in XRT. Great use of EIS.
At line 105 added 9 lines
*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.
At line 100 removed 3 lines
!SOT/FPP Instrument Status (Ted Tarbell)
!Data reduction & products
!Resulting physics information
At line 116 added 2 lines
!SOT Instrument
*BFI Characteristics ''is a great slide -- it explained a lot of the physics SOT was intended for.''
At line 119 added 118 lines
*NFI
Na I D shows very little difference from the Fe I magnetograms
6300 Å now has a degraded blocking filter that means it can't be used. Shame, because it's used by the SP.
*SP
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
ZnS coating on the H-alpha blocking filter means that it isn't routinely used, unless there's a special reason: AR, off-limb, key filament observations for a few hours.
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:
hinode.chiefobs@gmail.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.''
* Reduction
Shutterless mode for really fast Stokes parameters is possible but takes a little more work.
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
Shutterless
At line 245 added 98 lines
* HEM would be interested to put together a joint EIS XRT temperature distribution. (XRT: Reeves, Narukage; EIS: Warren, Mason)
(multi-filter data required; perhaps during SYNOP006? Could consider taking semi-regular datasets in co-ordination with this)
"hot stuff" can be done with another set of data.
* LKH thinks there’s a disconnect between horizontal magnetic fields
o EIS could potentially do something there WHADDAYA WANT?
temperature ranges of plasma observed in response to this emergence. Hot reconnection sites low down? Rapid cadence with a large temperature spread. Can be almost granule-sized, so detectable XRT/EIS. KM's programme in the QS might be suitable if there are SP data. XRT: taking long exposures with XRT to saturate on the bright points: ~40s Al_thin, exposing for everything else.
TB: HOP 89 study.
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.
see HOP 114.
----
* Prominence bubbles (HOP 73):
EIS: Brooks; SOT: Berger;
Bubbles are short lived, but would be good to go back over the older data.
XRT: boundary? TB: Cavity-appropriate studies. When bubbles go through the prominence, what happens?
EDL: are the cavities tied in or tied around? TB: around; recon events inject material? There may be a mass drainage route into the PIL.
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.
At line 118 changed one line
**Ted Tarbell
**Ted Tarbell ''(unable to attend)''
This page (revision-828) was last changed on 03-Feb-2017 10:35 by DenverTop