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

Work done and ongoing Digitization Cak v  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  Digitization process were completed. v  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 ]  

Raw image of the digitized CaK

First order calibrated image of the digitized CaK

The Raw and first order calibrated image of the digitized CaK

Second order calibrated image of the digitized CaK

First order calibrated image of the digitized CaK

The First and 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.

Contours of the region obtained from the intensity contrast threshold values greater than 1.12

Extracted network elements using the threshold values 1.006 (lower) and 1.12 (upper)

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 plage region

Profile of row cut that includes the network elements

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).

PLAGE

Enhance-network Active-Network

The following images represents the different features identified by our technique.

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.

THANK YOU