The CHARA Array Wiki

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== Fringe Offsets ======

The fringe offsets on any given night will depend on the POP configuration and the daily alignment. The table below gives a range of values where the fringes have been found for each cart on multiple nights across different POP configurations. The ranges should at least provide a guide for how far one might need to look to find fringes. The relative offsets between any pair of telescopes can be calculated from the differences between the ranges.

A new baseline solution was created on 2025May07 and has been set as the default on UT 2025May08. The solution is based on mircx/mystic observations from UT 2025Feb18 through 2025May07. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized). We used a limited date range in attempt to keep the offsets closer to zero. The following link shows the {{:chara:files:figure_optimal_2025may07.png?linkonly|sky coverage}} .

S1: 0.00 mm to +2.85 mm\\
S2: -0.45 mm to +1.94 mm\\
E1: -2.36 mm to +2.47 mm\\
E2: -0.51 mm to -2.96 mm\\
W1: -1.04 mm to +3.50 mm\\
W2: Reference Cart

The new solution is stored as the following backup file (also copied to telescopes.chara):\\
/ctrscrut/chara/etc/telescopes.chara.2025_05_07

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2025_04_09

{{:chara:files:baseline_offsets_2025_may_10_20.pdf|Offsets plotted against hour angle, elevation, and time for UT 2025 May 10 - 20.}}

----

A new baseline solution was created on 2024Jul08 and has been set as the default on UT 2024Jul11. The solution is based on mircx/mystic observations from UT 2024Apr04 through 2024Jul02. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized). We used a limited date range in attempt to keep the offsets closer to zero. The following link shows the {{:chara:files:figure_optimal_2024jul08.png?linkonly|sky coverage}} .

S1: -0.51 mm to +0.62 mm\\
S2: -0.78 mm to +0.12 mm\\
E1: -0.51 mm to +1.34 mm\\
E2: -1.62 mm to -0.26 mm\\
W1: -0.17 mm to +1.03 mm\\
W2: Reference Cart

The new solution is stored as the following backup file (also copied to telescopes.chara):\\
/ctrscrut/chara/etc/telescopes.chara.2024_07_08

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2024_06_27

{{:chara:files:baseline_offsets_2024_jul_11_12.pdf|Offsets plotted against hour angle, elevation, and time for UT 2024 Jul 11 - Jul 12.}}

----

A new baseline solution was created on 2024Jun27 and has been set as the default. The solution is based on mircx/mystic observations from UT 2023Jun28 through 2024Jun27. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized). We used an extended date range to improve {{:chara:files:figure_optimal_test_2024jun27.png?linkonly|sky coverage}} and cover more pop configurations.

S1: -0.50 mm to +0.65 mm\\
S2: -0.01 mm to +0.77 mm\\
E1: +0.23 mm to +2.40 mm\\
E2: +0.05 mm to +1.36 mm\\
W1: 1.13 mm to +2.91 mm\\
W2: Reference Cart

The new solution is stored as the following backup file (also copied to telescopes.chara):\\
/ctrscrut/chara/etc/telescopes.chara.2024_06_27

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2024_05_31

{{:chara:files:baseline_offsets_2024_jun28_29_30_jul01.pdf|Offsets plotted against hour angle, elevation, and time for UT 2024 Jun 28 - Jul 01.}}

----

A new baseline solution was created on 2024Feb28 and has been set as the default. The solution is based on mircx/mystic observations from UT 2023Apr15 through 2023Aug29. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized). We used an extended date range to improve sky coverage and cover more pop configurations.

The new solution is stored as the following backup file (also copied to telescopes.chara):

/ctrscrut/chara/etc/telescopes.chara.2024_02_28

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2023_08_29

----

A new baseline solution was created on 2023Aug29 and has been set as the default. The solution is based on mircx/mystic observations from UT 2023Apr15 through 2023Aug29. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized). We used an extended date range to improve {{:chara:files:figure_2023apr15_aug29_optimal.png?linkonly|sky coverage}} and cover more pop configurations.

S1: -0.8 mm to +0.1 mm\\
S2: -0.6 mm to -0.4 mm\\
E1: -0.8 mm to +0.3 mm\\
E2: -0.3 mm to +0.4 mm\\
W1: -0.2 mm to +0.4 mm\\
W2: Reference Cart

The new solution is stored as the following backup file (also copied to telescopes.chara):\\
/ctrscrut/chara/etc/telescopes.chara.2023_08_29

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2023_06_28

{{:chara:files:baseline_offsets_2023aug30.pdf|Offsets plotted against hour angle, elevation, and time for UT 2023 Aug 30.}}

----

A new baseline solution was created on 2023Jun28 and has been set as the default. The solution is based on mircx/mystic observations from UT 2023Apr15 through 2023Jun28. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized). The {{:chara:files:figure_2023apr15_jun28_optimal.png?linkonly|sky coverage}} improved compared with the last solution.

S1: -0.1 mm to +0.4 mm\\
S2: -0.6 mm to +0.2 mm\\
E1: -0.6 mm to +0.6 mm\\
E2: -0.3 mm to +0.3 mm\\
W1: -0.6 mm to +0.4 mm\\
W2: Reference Cart

The new solution is stored as the following backup file (also copied to telescopes.chara):\\
/ctrscrut/chara/etc/telescopes.chara.2023_06_28

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2023_05_10

{{:chara:files:baseline_offsets_2023jun29.pdf|Offsets plotted against hour angle, elevation, and time for UT 2023 Jun 29.}}

----

A new baseline solution was created on 2023May10 and has been set as the default. The solution is based on several nights of mircx/mystic observations from UT 2023Apr15 through 2023May09. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized). The {{:chara:files:figure_1_2023apr15_may09_optimal.png?linkonly|sky coverage}} was limited, but it seemed to converge on a reliable solution.

S1: -0.8 mm to +1.4 mm\\
S2: -1.2 mm to +0.7 mm\\
E1: -0.4 mm to +0.6 mm\\
E2: -0.9 mm to +0.3 mm\\
W1: -1.0 mm to +0.8 mm\\
W2: Reference Cart

The new solution is stored as the following backup file (also copied to telescopes.chara):\\
/ctrscrut/chara/etc/telescopes.chara.2023_05_10

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2023_02_20

{{:chara:files:baseline_offsets_2023may11_12.pdf|Offsets plotted against hour angle, elevation, and time for UT 2023 May 11-12.}}

----

A new baseline solution was created on 2023Feb20 and has been set as the default. The solution is based on mircx/mystic nights from UT 2022Nov11 through 2023Feb17. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized).

S1: -2.3 mm to -0.6 mm\\
S2: -2.3 mm to -1.0 mm\\
E1: 0.7 mm to +2.8 mm\\
E2: -1.0 mm to +3.0 mm\\
W1: 1.7 mm to +6.2 mm\\
W2: Reference Cart

The new solution is stored as the following backup file (also copied to telescopes.chara):\\
/ctrscrut/chara/etc/telescopes.chara.2023_02_20

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2022_09_07

{{:chara:files:baseline_offsets_2023apr15_16_17.pdf|Offsets plotted against hour angle, elevation, and time for UT 2023 Apr 15-17.}}

----

A new baseline solution was created on 2022Sep07 and has been set as the default. The solution is based on mircx/mystic nights from UT 2022Jul01 through 2022Sep07. It was created using Aaron's python baseline solution code (beams fixed; XYZ, light, and pops optimized).

S1: -0.9 mm to -0.1 mm\\
S2: -1.2 mm to +0.7 mm\\
E1: -1.1 mm to +0.4 mm\\
E2: -1.1 mm to +0.9 mm\\
W1: -1.4 mm to +0.2 mm\\
W2: Reference Cart

The new solution is stored as the following backup file (also copied to telescopes.chara):\\
/ctrscrut/chara/etc/telescopes.chara.2022_09_07

Load previous solution using the following command in ople:\\
initast /ctrscrut/chara/etc/telescopes.chara.2022_06_18

A new baseline solution was created on 2022Jun18 and has been set as the default.

S1: -0.7 mm to +0.5 mm\\
S2: -2.6 mm to +0.7 mm\\
E1: -0.3 mm to +0.4 mm\\
E2: -0.3 mm to +0.5 mm\\
W1: -3.8 mm to +0.4 mm\\
W2: Reference Cart

{{:chara:files:baseline_offsets_mystic_2022jun19_20.pdf|Offsets plotted against hour angle, elevation, and time for UT 2022 June 19-20.}}

A new baseline solution was created on 2022May19 and has been in use since 2022May22. There seems to be a small dependence on elevation for some of the telescopes.

S1: -1 mm on pop1 down to -6 mm on pop5 [note S1 optics removed and put back in for recoating]\\
S2: -0.8 mm to +0.3 mm\\
E1: -0.1 mm to +1.8 mm\\
E2: -0.7 mm to +0.9 mm\\
W1: +1.4 mm to +1.7 mm\\
W2: Reference Cart

{{:chara:files:baseline_offsets_mystic_2022may22_23_24.pdf|Offsets plotted against hour angle, elevation, and time for UT 2022 May 22-24.}}

A new baseline solution was created on 2022Mar21 and has been in use since 2022Apr03.

S1: -2.1 mm to 1.5 mm\\
S2: -0.8 mm to +0.6 mm\\
E1: +0.1 mm to +1.5 mm\\
E2: -0.1 mm to +3.5 mm\\
W1: +1.1 mm to +2.9 mm\\
W2: Reference Cart

{{:chara:files:baseline_offsets_2022apr_mix_new_old.pdf|See comparison of the old and new solutions}}.

Starting in 2022, it seems the baseline solution has drifted, and the offsets are again trending negative with increasing hour angle. Here are the ranges of recent offsets from March 2022 (look on the positive side of these ranges for early (-) hour angles and toward the negative side for late (+) hour angles):

S1: -0.5 mm to 3.8 mm\\
S2: -1.5 mm to +2.6 mm\\
E1: +1.5 mm to +4.4 mm\\
E2: -3.0 mm to +4.0 mm\\
W1: -0.5 mm to +4.5 mm\\
W2: Reference Cart

(hour angle +3 hr on negative side, hour angle -2 hr on positive side)

A new baseline solution was created on October 18, 2021 and accounts for changes in elevation. The offsets are more stable over the night, but there seems to be some differences between pop configurations. There is a new fringe predictor tool that plots offsets for the last 5 nights based on mircx headers. Log on to spooler@mircx and type "fringe_predictor" to see the mst recent offset vs. hour angle plots for each baseline.

S1: -0.2 mm to +1.2 mm\\
S2: -0.6 mm to +0.8 mm\\
E1: 0.5 mm to +2.0 mm\\
E2: -0.2 mm to +1.6 mm\\
W1: 1.0 mm to +3.0 mm\\
W2: Reference Cart

The offsets on S2 changed after the primary mirror recoating and realignment in September 2021. We are still using the baseline solution created July 29, 2021. The fringe offsets change rapidly with hour angle of the target. Early hour angles tend to have more negative offsets, positive hour angles tend to have more positive offsets. {{:chara:files:baseline_offsets_2021sep17_20.pdf|See plot of cart offset vs. hour angle}}. Fringes during 6T MIRCX observations on 2021 Sep 17 and 20 (W2 as reference cart):

S1: -2.5 mm to +1.0 mm\\
S2: -1.2 mm to +2.4 mm\\
E1: -2.4 mm to +1.0 mm\\
E2: -2.8 mm to +1.2 mm\\
W1: -3.5 mm to +0.8 mm\\
W2: Reference Cart

A new baseline solution was created on July 29, 2021. The fringe offsets continue to change rapidly over time depending on hour angle. See {{:chara:files:baseline_offsets_2021jul_aug.pdf|plot of cart offset vs. hour angle}}. Fringe offsets during 6T MIRCX observations on 2021 Jul 29, Aug, 02, Aug 06 (W2 as reference cart):

S1: -2.5 mm to +1.0 mm\\
S2: -2.0 mm to +0.6 mm\\
E1: -1.8 mm to +0.9 mm\\
E2: -1.5 mm to +1.0 mm\\
W1: -1.5 mm to +0.8 mm\\
W2: Reference Cart

Fringe offsets during 6T MIRCX observations in 2021 Mar-Apr (W2 as reference cart): For the current baseline solution, the fringe offsets change rapidly depending on hour angle. See {{:chara:files:baseline_offsets_2021mar_apr.pdf|plot of cart offset vs. hour angle}}.

S1: -2.0 mm to +2.0 mm\\
S2: -2.0 mm to +2.0 mm\\
E1: +0.0 mm to +3.0 mm\\
E2: +0.0 mm to +3.0 mm\\
W1: -1.5 mm to +2.0 mm\\
W2: Reference Cart

Fringe offsets during 6T MIRCX observations in 2020 June (W2 as reference cart):

S1: -0.7 mm to +1.1 mm\\
S2: -0.2 mm to +0.6 mm\\
E1: +0.2 mm to +0.8 mm\\
E2: +0.6 mm to +1.6 mm\\
W1: +0.8 mm to +1.3 mm\\
W2: Reference Cart

Fringe offsets during 6T MIRCX observations in 2019 July-August (W2 as reference cart):

S1: -1.3 mm to +0.2 mm\\
S2: -1.1 mm to +0.2 mm\\
E1: -2.0 mm to +0.5 mm\\
E2: -0.8 mm to +0.7 mm\\
W1: -0.6 mm to +0.2 mm\\
W2: Reference Cart

Fringe offsets during 6T MIRCX observations in 2019 July (W2 as reference cart):

S1: -0.8 mm to +0.2 mm\\
S2: -0.6 mm to +0.2 mm\\
E1: -1.1 mm to +0.5 mm\\
E2: -0.4 mm to +0.6 mm\\
W1: -0.2 mm to +0.2 mm\\
W2: Reference Cart

NOTE: Theo installed a new baseline solution on 2019Jun26. This is based on Aaron's most recent file merged with new numbers for beam off sets and internal airpaths as measured by Judit and Theo in the lab.\\
\\
Fringe offsets during 6T MIRCX observations on 2019 May 31 - June 2 (W2 as reference cart):

S1: -2.6 mm to -1.5 mm\\
S2: -2.6 mm to -1.7 mm\\
E1: +1.9 mm to +3.4 mm\\
E2: -2.5 mm to -1.0 mm\\
W1: +0.6 mm to +1.8 mm\\
W2: Reference Cart

NOTE: Theo installed a new baseline solution on 2019May09.\\
\\
NOTE: Theo installed a new baseline solution on 2019Apr12.\\
\\
Fringe offsets during 6T MIRCX observations on 2019 Apr 2+9 (W2 as reference cart):

S1: +3.0 mm to +4.4 mm\\
S2: +0.3 mm to +0.5 mm\\
E1: -0.4 mm to -2.3 mm\\
E2: +5.9 mm to +6.8 mm\\
W1: +6.3 mm to +8.9 mm\\
W2: Reference Cart\\
\\
NOTE: Theo installed a new baseline solution on 2019Feb20.\\
\\
Fringe offsets during 6T MIRCX observations after Phase 2 upgrades in 2018 September (W2 as reference cart):

S1: +4.3 mm to +6.5 mm\\
S2: +3.0 mm to +5.0 mm\\
E1: -3.0 mm to -0.7 mm\\
E2: +6.5 mm to +9.0 mm\\
W1: +6.0 mm to +7.5 mm\\
W2: Reference Cart\\
\\
Fringe offsets during 6T MIRC observations on 2018 Mar 29 (W2 as reference cart):\\
\\
W1: -0.3 mm to +1.4 mm\\
S2: +3.3 mm to +4.4 mm\\
S1: +1.4 mm to +2.1 mm\\
E1: +3.7 mm to +4.3 mm\\
E2: +3.3 mm to +4.2 mm\\
W2: Reference Cart\\
\\
NOTE: Theo installed a new baseline solution on 2018 Mar 22.\\
\\
Fringe offsets during 6T MIRC observations on 2017 Oct 26-27 (W2 as reference cart):\\
\\
W1: -4.0 mm to 2.7 mm\\
S2: -0.3 mm to +0.6 mm\\
S1: -2.0 mm to +0.4 mm\\
E1: -3.0 mm to +2.4 mm\\
E2: -2.0 mm to +1.5 mm\\
W2: Reference Cart\\
\\
NOTE: There might have been another baseline solution applied in August.\\
\\
Fringe offsets during 6T MIRC observations on 2017 July 9-10 (W2 as reference cart):\\
\\
W1: +5.6 mm\\
S2: +1.0 mm to +3.0 mm\\
S1: +0.8 mm to +3.1 mm\\
E1: +2.5 mm to +5.0 mm\\
E2: +1.0 mm to +3.1 mm\\
W2: Reference Cart\\
\\
Fringes offsets during CLIMB fringe searching on 2017 July 4 (W2 as reference):\\
E1: -1450 um to -1600 um\\
E2: -1450 um to -1900 um\\
S1: +2900 um to +3230 um\\
S2: +3380 um to +3650 um\\
W1: -500 um to -750 um\\
W2: Reference Cart\\
\\
NOTE: Theo ran a new baseline solution on 2017 June 08.\\
\\
Fringe offsets during 6T MIRC observations on 2017 March 18 (W2 as reference cart):\\
\\
W1: -15.9 mm to -18.4 mm\\
S2: 0.0 mm to -1.6 mm\\
S1: +0.5 mm to +1.1 mm (S1 fringe extrapolated from relative S1-S2 offset in previous configuration)\\
E1: +2.0 mm to +4.8 mm\\
E2: +3.3 mm to +6.5 mm\\
W2: Reference Cart\\
\\
NOTE: AO optics were installed in all remaining beams during 2017 Jan-Mar.\\
\\
Fringe offsets during 6T MIRC observations on 2016 June 18 - 2016 July 17 (W2 as reference cart):\\
\\
W1: -3.4 mm to +1.6 mm\\
S2: +0.8 mm to +5.3 mm\\
S1: +1.0 mm to +5.9 mm\\
E1: +2.4 mm to +6.6 mm\\
E2: +1.4 mm to +5.3 mm\\
W2: Reference Cart
The CHARA Array Wiki

User Tools

Site Tools

Page Tools
