---

Introduction:

Epsilon Aurigae is not like other variable stars. We will only get to see less than 1/14 of one cycle of the period over the next two years. Trying to create a phase plot or do time series/frequency domain analysis will not work. While there are multiple eclipses, each one has been unique.

However, we are treated to a rare opportunity to do an in-depth analysis of the data produced during this current eclipse. At HPO we will fill in as much data as we can from our observations, both photometric and spectroscopic. Other observers are encouraged to do the same. Comparisons and combining of observations can enhance the effort. At the end of the eclipse, all the data can be used to tell us a story about this mysterious star system. It will be up to us to piece together the puzzle parts and let a story emerge. Data from the 1982 -1984 eclipse are included for comparison.

Out -of-Eclipse HPO Data
December 2003 - April 2009

************	U Band	B Band	V Band
Avg Mag	3.7264	3.6050	3.0360
Max Mag	3.5369	3.4897	2.9289
Min Mag	3.9207	3.7168	3.1235
Difference	0.3838	0.2271	0.1946

1982 - 1984 Eclipse

INGRESS

********************	U Band	B Band	V Band
1st Contact	45,180	45,170	45,158
2nd Contact	45,300	45,305	45,300
Depth Mag	0.79	0.70	0.71
Slope (m/d)	0.0066	0.0052	0.0050
Ingress Time	120 d	135 d	142 d
Eclipse Period	9,885d	9,875d	9,863d

JD Dates are plus 2,400,000

Interpretation:

 

2009 - 2011 Eclipse

INGRESS (as of 22 Dec 09)

********************	U Band	B Band	V Band
1st Contact	55,054.208	55,054.469	55,056.345
2nd Contact	55,237.185	55,214.268	55,213.003
Depth Mag	?	?	?
Slope (m/d)	0.0043 D -0.0022	0.0044 D -0.0008	0.0045 D -0.0005
Ingress Time	183d D +63d	160d D +25d	157d D +15d
Eclipse Period	9,874d D -11d	9,884d D +09d	9,898d D +35d

JD Dates are plus 2,400,000

Interpretation Questions:
What does the period and change of period tell us?
What does the slope and depth of ingress tell us?

CONTACT DETERMINATION

 

2009 - 2011 Eclipse

TOTALITY

Mid-Eclipse	U Band	B Band	V Band
Mid Start	?	?	?
Mid Mid	?	?	?
Mid End	?	?	?
Mag Diff	?	?	?
Mid Length	?	?	?
Totality	?	?	?

JD Dates are plus 2,400,000

Interpretation Questions:
What does the length of totality tell us?
What does the mid-eclipse data tell us?

 

1982 - 1984 Eclipse

TOTALITY

Mid-Eclipse	U Band	B Band	V Band
Mid Start	45,495	45,492	45,485
Mid Mid	45,511	45,508	45,505
Mid End	45,528	45,524	45,524
Mag Diff	>0.20	>0.20	>0.20
Mid Length	16d	16d	20d
Totality	455d	437d	447d

JD Dates are plus 2,400,000

Interpretation:

 

2009 - 2011 Eclipse

EGRESS

********************	U Band	B Band	V Band
3rd Contact	?	?	?
4th Contact	?	?	?
Slope (m/d)	?	?	?
Egress Time	?	?	?
Eclipse Duration	?	?	?

JD Dates are plus 2,400,000

Interpretation Questions:
What does the slope of egress tell us?
What does the eclipse duration tell us?

 

1982 - 1984 Eclipse

EGRESS

********************	U Band	B Band	V Band
3rd Contact	45,755	45,742	45,747
4th Contact	45,810	45,813	45,812
Slope (m/d)	0.0144	0.0099	0.0109
Egress Time	55d	71d	65d
Eclipse Duration	630d	643d	654d

JD Dates are plus 2,400,000

Interpretation: