a Tutorial Part 5 – Setting up and performing differential photometry

a Tutorial Part 5 – Setting up and performing differential photometry

Image #

Julian Day

Δv

Gliese 876

0757-0840536

(C1)

Noise Error ± Mag
 Image Name

2

2453211.229

4.375

10.504

14.879

0.007

X2253V2470003CFT.fits

4

2453211.241

4.381

10.141

14.522

0.006

X2253V2470005CFT.fits

5

2453211.245

4.375

10.198

14.572

0.006

X2253V2470006CFT.fits

6

2453211.250

4.363

10.146

14.509

0.006

X2253V2470007CFT.fits

7

2453211.255

4.374

10.068

14.442

0.006

X2253V2470008CFT.fits

8

2453211.260

4.362

10.233

14.595

0.006

X2253V2470009CFT.fits

9

2453211.266

4.363

10.064

14.427

0.006

X2253V2470011CFT.fits

10

2453211.270

4.376

10.149

14.525

0.006

X2253V2470012CFT.fits

11

2453211.276

4.371

10.116

14.487

0.006

X2253V2470016CFT.fits

12

2453211.281

4.386

10.131

14.517

0.006

X2253V2470017CFT.fits

13

2453211.285

4.366

10.275

14.641

0.006

X2253V2470018CFT.fits

14

2453211.288

4.371

10.269

14.640

0.006

X2253V2470019CFT.fits

15

2453211.291

4.372

10.119

14.491

0.006

X2253V2470020CFT.fits

16

2453211.296

4.373

10.157

14.530

0.006

X2253V2470023CFT.fits

17

2453211.298

4.372

10.192

14.564

0.006

X2253V2470024CFT.fits

18

2453211.302

4.366

10.545

14.911

0.007

X2253V2470025CFT.fits

19

2453211.305

4.371

10.932

15.303

0.009

X2253V2470026CFT.fits

20

2453211.309

4.350

11.070

15.420

0.010

X2253V2470027CFT.fits

21

2453211.313

4.386

10.193

14.579

0.006

X2253V2470029CFT.fits

22

2453211.316

4.369

10.258

14.627

0.006

X2253V2470032CFT.fits

23

2453211.319

4.366

10.236

14.602

0.006

X2253V2470033CFT.fits

24

2453211.324

4.374

10.297

14.671

0.006

X2253V2470034CFT.fits

25

2453211.327

4.368

10.284

14.652

0.006

X2253V2470035CFT.fits

26

2453211.330

4.375

10.314

14.689

0.007

X2253V2470036CFT.fits

27

2453211.333

4.383

10.332

14.715

0.007

X2253V2470037CFT.fits

28

2453211.337

4.397

10.265

14.662

0.006

X2253V2470040CFT.fits

29

2453211.341

4.369

10.375

14.744

0.007

X2253V2470041CFT.fits

30

2453211.344

4.386

10.366

14.752

0.007

X2253V2470042CFT.fits

31

2453211.348

4.355

10.464

14.819

0.007

X2253V2470043CFT.fits

32

2453211.351

4.386

10.770

15.156

0.010

X2253V2470044CFT.fits

Avg

4.373

10.315

14.688

Max

4.397

11.070

15.420

Min

4.350

10.064

14.427

Range

0.047

1.006

0.993

Max – Avg

0.024

0.755

0.732

Avg – Min

0.023

0.251

0.261

It is not unusual for one observatory to want to blend its data with
the data obtained from one or more other observatories to obtain greater
confidence in a research outcome. 
However each observatory will typically have a different filter/CCD
combination.  Each filter will differ
from a perfect band pass match for the ideal U, B, V, R, or I filters and no
two CCD chips will have exactly the same response over their entire spectrum of
sensitivity; therefore, certain procedures have been developed that are meant
to compensate for this fact.  They
involve calculations that will effectively convert raw magnitude differences to
standard magnitude differences and allow direct comparison of data from
different observatories. (Benson 42)  A
discussion of these calculations will begin in the next paragraph.  If you are not going to be blending your
observation data with observations done at another location, you can skip to
the part of this documentation labelled Analysis of the Photometric Data.

Star

V-I

v-i

v

i

G876

1.704

2.930

10.119

7.189

1.704

2.826

10.193

7.367

1.704

2.903

10.332

7.429

C1

0.980

0.855

14.491

13.636

0.980

0.783

14.579

13.796

0.980

0.849

14.715

13.866

C2

1.22

1.304

16.429

15.125

1.22

1.131

16.506

15.375

1.22

1.138

16.645

15.507

Image_#

Julian Day

ΔV

Δv

± Error

 (SNR+σ)

2

2453211.229

4.129

4.375

0.017

4

2453211.241

4.135

4.381

0.016

5

2453211.245

4.128

4.374

0.016

6

2453211.250

4.117

4.363

0.016

7

2453211.255

4.128

4.374

0.016

8

2453211.260

4.116

4.362

0.016

9

2453211.266

4.117

4.363

0.016

10

2453211.270

4.130

4.376

0.016

11

2453211.276

4.125

4.371

0.016

12

2453211.281

4.140

4.386

0.016

13

2453211.285

4.120

4.366

0.016

14

2453211.288

4.125

4.371

0.016

15

2453211.291

4.126

4.372

0.016

16

2453211.296

4.127

4.373

0.016

17

2453211.298

4.126

4.372

0.016

18

2453211.302

4.120

4.366

0.017

19

2453211.305

4.125

4.371

0.019

20

2453211.309

4.104

4.350

0.020

21

2453211.313

4.140

4.386

0.016

22

2453211.316

4.123

4.369

0.016

23

2453211.319

4.120

4.366

0.016

24

2453211.324

4.128

4.374

0.016

25

2453211.327

4.122

4.368

0.016

26

2453211.330

4.129

4.375

0.017

27

2453211.333

4.137

4.383

0.017

28

2453211.337

4.151

4.397

0.016

29

2453211.341

4.123

4.369

0.017

30

2453211.344

4.140

4.386

0.017

31

2453211.348

4.109

4.355

0.017

32

2453211.351

4.140

4.386

0.020

Avg

4.127

4.373

Max

4.151

4.397

Min

4.104

4.350

Range

0.047

0.047

Max-Avg

0.024

0.024

Avg-Min

0.023

0.023

FWG
(FITS Working Group), Definition of the Flexible Image Transport System
(FITS), International Astronomical Union, (2008) 1-131

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