Status of Solar Coronal Dopplerometer

Ken Phillips (KJHP) on behalf of 
Pawel Rudawy (PR), Arek Berlicki (AB), Krzysztof Radziszewski (KR), 
Francis Keenan (FPK)

The idea of a solar coronal dopplerometer originated in 2010-2011, after the 
publication of our 2001 eclipse results (Rudawy et al. 2010, Sol. Phys. 267, 305) 
indicated that there were no obvious signs of oscillations in the total intensity 
in the coronal green line during the 2001 Zambia eclipse. 
However, Steve Tomczyk's 2007 results with his CoMP instrument indicated that 
there were wave motions in and around active regions as shown by Doppler motions 
in the near-infrared Fe XIII lines, with periods of tens of seconds. 
The idea was to look for similar Doppler motions with much shorter periods 
(~1 second) which might be important for coronal heating.

KJHP raised the idea of having two filters tuned to the green line 
(5303 +/- 1 Angstroms or so) with cameras similar to the old SECIS 
ones used in 2001 and other eclipses. PR suggested an improved idea - 
having a small version of MSDP (similar to the one used in KR's H-alpha 
flare observations with the Wroclaw Bialkow telescope) to isolate radiation 
from the green line. 

PR contacted Pierre Mein who then designed a system that, it was believed, 
might be used not only at eclipses but also on one of the 2 telescopes of 
the Lomnicky Stit coronagraph. Jan Rybak was contacted but he expressed 
concern that the equipment was much too heavy to be mounted on the coronagraph. 
Also, there was now a commitment to have another CoMP instrument from 
Steve Tomczyk on one coronagraph, which was built and (partially?) ready 
by the end of 2011. PR had the idea of an optical fibre output from the 
telescope to connect to the MSDP which would not be mounted on the coronagraph. 

Meanwhile, FPK (Belfast) expressed interest and offered us financial 
assistance for the building of either the MSDP or the new Andor camera 
which we considered as a replacement for the SECIS cameras (they dated back 
to 1997 and were first used for the 1998 and 1999 eclipses). 

KR and PR took delivery of a new camera - Andor 885 iXon - which is now 
installed at the Bialkow observatory. Our old Photometrics camera 
(Photometrics SenSys KAF 1400-01 with good quality CCD - 1317x1035) is 
also available for tests or observations.   

Dr Mein's design for the MSDP was sent to our team in March 2012, but 
it was clear that it was unnecessarily elaborate (18 channels with 
microslicers across the green line) with a cost of about 37,000 euros,
 much beyond the amount that FPK had available. KJHP contacted Dr Mein 
in May 2012 about "de-scoping" the design, and had a reply on June 11, 
saying that a much reduced optical arrangement could be designed, with 
a single cylindrical mirror. There would be a slight disadvantage of a 
mixing of wavelengths of neighbouring channels. This seemed to us much 
more desirable, and would probably fit in with the amount of funding 
FPK had available. 

In a visit to Belfast (June 12), FPK said that there were other funding 
possibilities also, through the US Air Force. 

There is concern that the corona would be very faint, especially if 
observations were delayed until well after the peak of the current solar cycle. 
Some test runs were made by PR and KR in April 2009, but no coronal structures 
were visible. However, the activity level on that occasion was extremely low. 
The experience of Steve Tomczyk's team in their 2011 observations would be 
helpful to evaluate expected signal levels for our instrument. 

In summary, the instrument (called either SCD DOMS or SCODL- we haven't 
decided on the name yet!) is still very much in the design phase but there 
is money available for the building of the MSDP, an essential part of the 
instrument, and the camera has already been bought. If the coronagraph at
Lomnicky Stit were available, then we would complement Dr Tomczyk's CoMP 
observations which in general would be looking at longer-period wave motions, 
while we would be searching for 1-second-period wave motions. Concerns about 
the weight of the MSDP might be avoided with optical fibre connections, but 
this would have to be designed. If the coronagraph were not available, then 
we would concentrate our efforts on total eclipses. Two suitable ones are due 
to occur in the next 5 years, one in northern Norway (at a Polish station in 
Spitzbergen), the other across the continental USA. Other coronagraphs are 
also a possibility.