An on-sky investigation into factors limiting the performance of Keck-NIRC2 for conducting infrared high-contrast imaging
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866914027918065664 |
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| author | Bowens-Rubin, Rachel Salama, Maïssa Nguyen, Jayke S. Thompson, William Hinz, Philip |
| author_facet | Bowens-Rubin, Rachel Salama, Maïssa Nguyen, Jayke S. Thompson, William Hinz, Philip |
| contents | The most common instrument used by the exoplanet/brown dwarf direct imaging community at the W.M. Keck Observatory is currently the NIRC2 near-infrared imager. We performed on-sky testing to investigate three effects which may be limiting the performance of NIRC2 when conducting high-contrast imaging observations from $3-5μ$m. First, we report the measurements of an on-sky test of the throughput of the L/M vector vortex coronagraph. We quantify the throughput and additional background flux penalties, noting that the performance effects of using the vector vortex coronagraph in the Ms-filter are greater than in the Lp-filter. Second, we utilize the recently commissioned NIRC2 electronics upgrade to measure the sky variability at sub-second speeds. We find that the background varies at timescales of less than 30s, indicating that the electronics upgrade may open an opportunity to improve the sky-background subtraction of future surveys. Third, we document the contribution of the image derotator to the spatial non-uniformity in the background flux. We conclude by giving a set of recommendations of how the Keck-NIRC2 high-contrast imaging community can adapt their observing strategies to improve the sensitivity of future surveys. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_07138 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | An on-sky investigation into factors limiting the performance of Keck-NIRC2 for conducting infrared high-contrast imaging Bowens-Rubin, Rachel Salama, Maïssa Nguyen, Jayke S. Thompson, William Hinz, Philip Instrumentation and Methods for Astrophysics The most common instrument used by the exoplanet/brown dwarf direct imaging community at the W.M. Keck Observatory is currently the NIRC2 near-infrared imager. We performed on-sky testing to investigate three effects which may be limiting the performance of NIRC2 when conducting high-contrast imaging observations from $3-5μ$m. First, we report the measurements of an on-sky test of the throughput of the L/M vector vortex coronagraph. We quantify the throughput and additional background flux penalties, noting that the performance effects of using the vector vortex coronagraph in the Ms-filter are greater than in the Lp-filter. Second, we utilize the recently commissioned NIRC2 electronics upgrade to measure the sky variability at sub-second speeds. We find that the background varies at timescales of less than 30s, indicating that the electronics upgrade may open an opportunity to improve the sky-background subtraction of future surveys. Third, we document the contribution of the image derotator to the spatial non-uniformity in the background flux. We conclude by giving a set of recommendations of how the Keck-NIRC2 high-contrast imaging community can adapt their observing strategies to improve the sensitivity of future surveys. |
| title | An on-sky investigation into factors limiting the performance of Keck-NIRC2 for conducting infrared high-contrast imaging |
| topic | Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2509.07138 |