Checklist for PN.S Halpha Camera

This file is outdated and is kept for reference. It should not be added to.

go to the PN.S Halpha Camera

CONTACTS (at ING and PN.S respectively):

Technical: Romano Corradi (rcorradi@ing.iac.es)     Nigel Douglas (ndouglas@astro.rug.nl)

Organisation: Rene Rutten (rgmr@ing.iac.es)     Koen Kuijken (kuijken@astro.rug.nl)

ITEM SUMMARY COMMENTS
A DATE INDICATES A MESSAGE, SEE "Correspondence" FOR DESCRIPTION
Shutters (1) How many are required, what is their size, how are they driven Nigel assumes 2, iris type, with a single (commercial) controller and a single RS 232 interface
Shutters (2) Cassegrain Matt or John to check on suitability of the shutters at Cass, with respect to EM noise and space/size limitations
Filters WFC size, one wide-band one narrow (what was decided about filter operation? - can we move both filters independently?) It was agreed that filter insertion would be driven by the 12v (check!) minimotors already used by the shutter and focal plane mask. N.B. the filters are not tiltable!!??
Optical Design spots are at pns->project->optical design

enclosed power has been calculated, same location
email N.D. 27/5/04 (more info requested!?)

email N.D. 15/6/04 (results satisfactory)

TNG v WHT: Damien wrote (28/5/2004) "I have specified that the last group of 2 lenses in the H-alpha camera be different for each telescope" and a similar situation is the case in the PN.S main cameras. So a change of optics would be required to get best quality at the TNG.

ACTION: verify these statements with Damien
Dichroic Notes are here Gabe has a preference for the ZC&R design, Nigel has a preference for CSIRO. HOWEVER: both are OK from the H-alpha point of view. What is currently holding up things is the lack of data at 5007: Nigel's priority is to know what impact the dichroic has on the [OIII] transmission. Gabe requested this of ZC&R in emails around January 7 but I am not aware of other correspondence.
transportation the shipping contact at LPO is Juan Martinez
(juan@ing.iac.es) phone +34 922 425414
 
instrument readiness mostly at RSAA  
commissioning who? when? The flexure issue has been discussed (see below) but we do need a plan of attack should it prove necessary. ND feels strongly that resources should be available so that JH can be in the commissioning (and post-commissioning!) team


Current Problems 09 April 2004 (KCF)

Opto-mechanical design work on the H-alpha arm is currently stalled

We need to get the process restarted - Ortwin's money has a deadline for completion

Matt Doolan needs answers to the following questions before he can complete his design work.

1) Is the optical design acceptable ?

Following our telecon in February, then plan was to get spot diagrams from Damien that were well enough populated so that Koen could run them through his convolution program and see how the seeing-convolved point images would look. This process was delayed because Damien and Matt have had some problems getting mail to NL.

* Where are we now in this process ?

* Do Nigel/Koen have the data from Damien ?

* Can we make a decision quickly about the optical design - is it acceptable ?

Matt cannot do the details of the optical mountings until we make this decision.

added 14-04-2004 by KK

I have not received any spots to convolve. I did not think that there was a real issue, the spot diagrams looked pretty convincing. But if you send me spots I will convolve them!

2) Can we mount the third dewar (the H-alpha camera dewar) using the same mounting arrangement as for the main PNS CCDs, with the same clearances ?

Here is the problem as I understand it:

The dewar and its mounting need to fit between the capstans. Matt understands that the third dewar has a bayonet mounting, so a bayonet adapter will be needed. This adapter would go on the plate which moves when the capstans are turned. Is there enough clearance between the capstans (as in the original PNS CCD mounting) to accept this bayonet adapter ?

added 14-04-2004 by KK

I am confused... here is what I know:
At ING we are told that the cryostats all have identical interface plates, so anything that works on the EEV12 and EEV13 devices in use now should also work here. In fact Marconi2 has already been mounted, and fits on the existing arms (but was 1mm out of focus range).


(3) Matt needs to know the distance between the dewar window and the CCD, and also the thickness of the dewar window. He needs to know this because the last lens in the camera module mounts close to the dewar window.

added 15-04-2004 by KK

Information from Simon Tulloch at ING:
the optical distance (the physical distance is about 1.6mm greater) between front of window and CCD is about 11mm (+/-1mm), the window is physically 4mm thick (fused Silica) and it is recessed by 2.5mm from the front of the faceplate.

* It would be a great help to the project if those of you with ING contacts could find out the answers to questions (2) and (3). Please let me know if the issues are not clear


We still have an issue about flexure.

In summary, Nigel remains concerned about flexure of the PNS when the H-alpha arm is mounted. John Hart has calculated the flexure and believes it is not a problem. Matt gave us an estimate of the cost of a FEA and it was timeconsuming and expensive. Nigel suggested a compromise, that John Hart might make a visit to LPO and make an on-site assessment of the situation. He is willing to do this, but it would cost us for his time and expenses. He has not given me an estimate of the total cost, but I would guess that it would be at least $5000 (AUD), maybe a bit more but less than the cost of an FEA, depending on how long we would like him to stay. Please let me know your opinion about this.

Flexure Tests added 14-04-2004 by KK+AR

On a cold and snowy night we ran extensive flexure tests with the PN.S. (runs 661364-435, 14 April 2004). We went down to 10 degrees above the horizon, and back to zenith, taking arcs every 20 degrees of elevation. Test was done at four mount position angles: L or R arm up, and round or square hatch up. The results are summarized in the figures below. There is flexure, but it is quite different in the two arms. R appears much stiffer than L. This is a concern, but good news for the halpha arm: the tube itself is quite stiff or the flexure would be seen in both arms and at all orientations. This suggests that adding more load to the tube would not cause a lot of bending of the main tube, which apparently verifies John's original claim.

The figures show the path taken by a spot in an arc exposure over the course of a slew from zenith (left) to near the horizon (right) and back up. x (dispersion) and y position of the spots in both arms are plotted. Units are pixels (45km/s and 0.3arcsec). Four figures for four different position angles of the instrument rotator. (Click on them for postscript versions.)




The effect looks bad, but is still OK though. At worst over a half-hour exposure the elevation changes by 7 degrees. This can give a 1-pixel shift, degrading the image but not at all badly. The shift also causes a calibration uncertainty of ca. half a pixel (half of the shift cf. a preceding mask). As the effect comes mainly from one arm, the zeropoint uncertainty that results is about 1/4 pixel, or 10km/s. At worst.

(last revised June 17 2004)

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