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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

32541 results found.

  1. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  2. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  3. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  4. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  5. EP240426a: YAHPT optical upper limit
  6. XMM-Newton observation of EP240426a
  7. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  9. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  10. GRB 240414A: NOEMA detection
  11. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  12. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  13. EP240426a: GMG optical upper limit
  14. LVK S240422ed: Further Swift-XRT followup of three sources
  15. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  16. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  18. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  19. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  20. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  21. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  22. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  23. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  24. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  25. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  26. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  27. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  28. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  29. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  30. LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
  31. LIGO/Virgo/KAGRA S240422ed: ANU 2.3m followup of candidate counterparts
  32. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  33. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  34. GRB 240419B: Swift-BAT refined analysis
  35. GRB 240421B: Swift-BAT refined analysis
  36. GRB 240422A: Glowbug gamma-ray detection
  37. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  38. LIGO/Virgo/KAGRA S240413p: DESGW DECam Follow-Up
  39. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  40. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  41. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  42. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  43. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  44. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  45. LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
  46. LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts
  47. LIGO/Virgo/KAGRA S240422ed: MOSFIRE imaging of the DECam GW-MMADS candidate AT 2024hdm
  48. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  49. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  50. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  51. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  52. LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
  53. LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated.
  54. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  55. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  56. GRB 240421B: GRBAlpha detection
  57. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  58. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  59. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  60. LIGO/Virgo/KAGRA S240422ed: LAST optical observations
  61. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  62. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  63. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  64. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  65. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  66. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  67. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  68. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  69. GRB 240419A: Swift-BAT refined analysis
  70. GRB 240418A: Swift-BAT refined analysis
  71. LXT240402A/GRB240402B: Chandra X-ray detection
  72. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  73. GRB 240419A: Possible ATCA radio detection
  74. GRB 240421B: ATCA radio observations
  75. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  76. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  77. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  78. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  79. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  80. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  81. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  82. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  83. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  84. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  85. GRB 240421A: Glowbug gamma-ray detection
  86. GRB 240414A: radio detection with the VLA
  87. Fermi-LAT gamma-ray observations of IceCube-240419A
  88. GRB 240414A: AMI-LA radio observations
  89. GRB 240414A: LBT optical detection
  90. GRB 240419B : MITSuME Akeno optical upper limits
  91. Fermi GRB 240422A: Global MASTER-Net observations report
  92. GRB 240421B: AstroSat CZTI detection
  93. Fermi GRB 240421B: Global MASTER-Net observations report
  94. Swift GRB 240421B: Global MASTER-Net observations report
  95. GRB 240421B: Fermi GBM Observation
  96. GRB 240421B: J-band upper limits from WINTER
  97. GRB 240421B: Swift/UVOT Upper Limits
  98. Fermi GRB 240421A: Global MASTER-Net observations report
  99. EP240417a: no counterpart detection by SOAR
  100. EP240420a: TNT upper limit to its optical counterpart

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