## Re: [guide-user] eclipse timing

bob Aug 23, 2017

I just read the help about dynamical time (TD) and then delta-t and it says it uses a formula for future delta-t.
I did the quick info under help and it shows a delta-t of 68.7. which is very close to what you used below of 68.9.

On 8/23/2017 5:01 PM, bob bob@bobsbits.net [guide-user] wrote:

How does guide compensate for leap seconds?
We do need to know the leap seconds elapsed to convert from T1 to UTC. Yes?
I have not updated guide in years(15 yrs?). So how do I input leap seconds in guide?

On 8/23/2017 4:07 PM, Luc Desamore luc_desamore@yahoo.ca [guide-user] wrote:

It could have something to do with  limb effect (real vs mean limb)

Luc

From occult 4.3.2.0 : (with limb effect)

S O L A R     E C L I P S E     P R E D I C T I O N   for 2017 Aug 21

East Longitude - 88  6.00
Latitude   37  4.10
Altitude  0 m.

TT-UTC  69.2 secs    Prediction basis: DE430
UT1-UTC  0.2 secs    ▲T [= TT-UT1]  68.9 secs

Event               UTC       P.A.   alt.      Differential Corrections
h  m  s       o      o          A       B       C
First Contact    16 55  6     293     61         2.10   -0.59   -0.03
Baily beads @2nd 18 23  1
Second Contact   18 23  9.5   120.9
Maximum Eclipse  18 24 30             64         2.06   -1.25   -0.01
Third Contact    18 25 49.3   293.4
Baily beads @3rd 18 25 56
Last Contact     19 50 23     114     54         1.62   -1.68    0.01
[2nd and 3rd contacts are based on the lunar limb derived from LRO LOLA]

Magnitude at Maximum Eclipse 1.013
Magnitude (diameter ratio)   1.031

_______________________________________________________________________________

without limb effect :

S O L A R     E C L I P S E     P R E D I C T I O N   for 2017 Aug 21

East Longitude - 88  6.00
Latitude   37  4.10
Altitude  0 m.

TT-UTC  69.2 secs    Prediction basis: DE430
UT1-UTC  0.2 secs    ▲T [= TT-UT1]  68.9 secs

Event               UTC       P.A.   alt.      Differential Corrections
h  m  s       o      o          A       B       C
First Contact    16 55  6     293     61         2.10   -0.59   -0.03
Second Contact   18 23 11     122
Maximum Eclipse  18 24 30             64         2.06   -1.25   -0.01
Third Contact    18 25 50     286
Last Contact     19 50 23     114     54         1.62   -1.68    0.01

Magnitude at Maximum Eclipse 1.013
Magnitude (diameter ratio)   1.031

On 2017-08-23 20:40, bob davis bob@bobsbits.net [guide-user] wrote:
So I am chasing down an anomaly of the timing...

I was at
37.06769 -88.10091
which is down to a 1.112 meter

Nasa google maps showed totality begging at.

and guide8.0 showed the following:

I timed it at:
13:23:08

I wonder if it has something to do with leap seconds?

```--
Bob Davis
Exeter NH 03833
603-778-0781```

```--
bob davis
```--