SCIENCE USING KODAIKANAL DIGITIZED DATA By V. MuthuPriyal IIA Kodaikanal
On going data digitization in kodaikanal observatory l Ca-K line spectroheliograms 1904-2007(41000) l Whitelight photoheliograms-1904-till date (44000) l H-alpha spectroheliograms 1904 1999 (38000) l K-pr spectroheliograms 1908 2002 (34000)
People Involved in this project Prof. Jagdev Singh Dr. B. Ravindra Mr. Selvendran Ms.Nazia Afreen Ahmed Ms.Amareswari Ms.Fathima Khyrun Mr.Sathish Prof. Dipankar Banerjee Ms.V. MuthuPriyal Mr. Kumaravel Ms.T.G.Priya Ms.AyshaBanu Mr.Kamesh Ms.Janani
Digitized Image (White Light) The following sample image depict the digitized solar image observed through white light 2011-12-28T07:50
Digitized Image (Ca + K line) The following sample image depict the digitized solar image observed through Ca + K 1978-01-04T02:33
Digitized Image (H-alpha line) The following sample image depict the digitized solar image observed through H-alpha 1978-01-01T05:04
Cak v Work done and ongoing Digitization Our team completed the Digitization of CaK images. v First order calibration cleaning up and aligning to north up - around 70 years have been completed. v Second order calibration Limb Darkening correction - around 30 years have been also completed recently. Whitelight v v Digitization process were completed. First order calibration also carried out simultaneously H-alpha v Digitization process ongoing related to H-alpha image and 2 years data were digitized.
Processing steps involved in CaK calibration First Order Calibration: 1. Correction for image rotation 2. Cleaning up the image 3. Flat fielding Second order calibration: 1. Finding Center (X0,Y0),radius fitting a circle to a limb points 2. Removal of limb darkening [singh et al., Research in Astronomy and Astrophysics, October-2011 ]
The Raw and first order calibrated image of the digitized CaK Raw image of the digitized CaK First order calibrated image of the digitized CaK
The First and Second order calibrated image of the digitized CaK First order calibrated image of the digitized CaK Second order calibrated image of the digitized CaK
Digitized data available in our website Kodai Server hosted@ IIA Data center: 100 years of Cak and White light raw data (fits files) are available through a searchable online portal developed (in house) at IIA. Java scripting and Mysql database has been used to develop this portal. Java developer team : Ms. Sneha, Drs. Rekhesh Mohan & D. Banerjee All data will be available for quick look inspection followed by a easy download option through a dedicated server at IIA data center The URL is http://kso.iiap.res.in/
Sample Ca K Calibrated image from the Archive
Kodaikanal Twin Telescope Data Archive
Data Search Engine
The Proposed Research projects with Digitized data 1. Long term variations in the photospheric and chromospheric rotation rate 2. Variation of tilt angle with the solar cycle phase and its implication to the helicity and solar dynamo. 3. Variation in the size of the sun with the phase of solar cycle. 4. Variation of background flux with the phase of solar cycle 5. Variation in the polar regions with the phase of the solar cycle 6. Solar activity and its association with magnetic cycle 7. Irradiance variations 8. Archival of large data base in digital form
Procedure involved to compute the TwinTelescope CaK data sample science problem Procedure followed in this Work to identify network cells are: 1. Limb fitting to identify the image center and radius of the solar disk. 2. Removal of limb darkening 3. Polynomial fitting and thresholding. The said procedures were utilized to compute the second order calibration of CaK digitized data. Determination of the chromospheric quiet Network element area index and its variation during 2008-2011, Jagdev Singh et.al., accepted in Research in Astron. Astrophys, October-2011. In that paper we found that during the extended period of minimum activity, it is observed that the network element area index decreases by about 7%compared to the area occupied by the network elements in 2008.
Extracted network elements using the threshold values 1.006 (lower) and 1.12 (upper) Contours of the region obtained from the intensity contrast threshold values greater than 1.12
Intensity profile along a row of the image corrected for limb-darkening effect. The image obtained after the limb darkening correction and polynomial fitting. Profile of row cut that includes the network elements Profile of row cut that includes the plage region
Contours of the region I and II obtained from the intensity contrast threshold values of 1.006 (lower) and 1.12 (upper)
Daily average value of the network element area index (Narea %), Plage area index (Parea, %) and Sunspot area index (Sarea,%) for the period Feb,2008-Feb,2011.
Science involved in our digitized data Ca-K 1) Long term variation in the chromospheric rotation rate. We have plans to estimate long term variation in the chromospheric rotation rate using soft ware developed program after several attempts made on the above said parameter as done previously reported research article using limited data. (Ref: Variation in the solar rotation rate derived from Ca-K plage areas by Jagdev Singh et.al., 1984) 2) Variation of background flux, plage index and network index with solar cycle phase. Our computed program will be utilized to estimate the preliminary parameters such as plages, enhanced network, active-network and network and these extracted values implies the above said two parameters (1) and (2). (Ref: Evolution of chromospheric structures derived from CaII K spectroheliograms by John R. Worden et.al, 1998).
The following images represents the different features identified by our technique. Enhance-network Active-Network PLAGE
Network Elements
Whitelight 1) Long term variation in the photospheric rotation rate. The preliminary attempts are going on to develop the program for further finding the long term variation in the photoshperic rotation rate, tilt angle of sun spots etc.
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