Exceptionally high systemic velocity star

[howardisaacson]

The star HIP112486 has a systemic RV of -269 km/s. The result is that the Cross correlations are flat. The current L0 files have a value of 0 for TARGRADV. I think if these are updated, the high systemic RV can be accounted for. ex: https://jump.caltech.edu/observing-logs/kpf/KP.20231124.16822.76

[bpholden]

The FITS header keyword TARGRADV comes from the telescope control system, and not from the kpfconfig service (that is where newer keywords like the GAIA ID come from.) To be filled in, the starlist must include the value. It is possible that the value could be directly written to the dcs service by the observing software. Otherwise, we need a separate way to include that information. I could replicate the keyword but make it part of kpfconfig.

On Tue, Jan 16, 2024 at 10:40 AM Howard Isaacson @.***> wrote:

The star HIP112486 https://jump.caltech.edu/star/hip112486 has a systemic RV of -269 km/s. The result is that the Cross correlations are flat. The current L0 files have a value of 0 for TARGRADV. I think if these are updated, the high systemic RV can be accounted for. ex: https://jump.caltech.edu/observing-logs/kpf/KP.20231124.16822.76

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[howardisaacson]

Thanks Brad. I think I found that the OB can populate TARGRADV, along with Teff.

Star: T005398 from the OB: RadialVelocity: -10.23 Example of Obs with populated TARGRADV: KP.20240116.53318.31 I did find one example that did not populate TARGRADV: KP.20240116.38119.81

I confirmed for these other two stars that TARGRADV is being populated appropriately.

star 217014 The OB populates the Radial Velocity and it shows up in TARGRADV eg: KP.20240116.22283.38

star: 10700, The OB does not populate TARGRADV KP.20240116.23649.71

On Tue, Jan 16, 2024 at 9:05 PM Brad Holden @.***> wrote:

The FITS header keyword TARGRADV comes from the telescope control system, and not from the kpfconfig service (that is where newer keywords like the GAIA ID come from.) To be filled in, the starlist must include the value. It is possible that the value could be directly written to the dcs service by the observing software. Otherwise, we need a separate way to include that information. I could replicate the keyword but make it part of kpfconfig.

On Tue, Jan 16, 2024 at 10:40 AM Howard Isaacson @.***> wrote:

The star HIP112486 https://jump.caltech.edu/star/hip112486 has a systemic RV of -269 km/s. The result is that the Cross correlations are flat. The current L0 files have a value of 0 for TARGRADV. I think if these are updated, the high systemic RV can be accounted for. ex: https://jump.caltech.edu/observing-logs/kpf/KP.20231124.16822.76

— Reply to this email directly, view it on GitHub https://github.com/Keck-DataReductionPipelines/KPF-Pipeline/issues/781,

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Howard Isaacson Research Scientist in Astronomy University of California, Berkeley

[bjfultn]

We really want to be populating the TARGRADV since it defines the center of the CCF window and the initial guess for the fits to the CCF. Not having it will have a small, but measurable effect on the RV precision at best, and at worst we'll miss the peak entirely like we did for this star.