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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').

22274 results found.

  1. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  2. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  3. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  4. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  5. LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
  6. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  7. GRB 240419B: Swift-BAT refined analysis
  8. GRB 240421B: Swift-BAT refined analysis
  9. GRB 240422A: Glowbug gamma-ray detection
  10. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  11. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  12. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  13. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  14. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  15. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  16. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  17. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  18. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  19. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  20. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  21. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  22. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  23. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  24. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  25. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  26. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  27. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  28. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  29. GRB 240419A: Swift-BAT refined analysis
  30. GRB 240418A: Swift-BAT refined analysis
  31. LXT240402A/GRB240402B: Chandra X-ray detection
  32. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  33. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  34. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  35. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  36. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  37. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  38. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  39. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  40. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  41. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  42. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  44. GRB 240421A: Glowbug gamma-ray detection
  45. GRB 240414A: radio detection with the VLA
  46. Fermi-LAT gamma-ray observations of IceCube-240419A
  47. GRB 240414A: AMI-LA radio observations
  48. GRB 240414A: LBT optical detection
  49. GRB 240419B : MITSuME Akeno optical upper limits
  50. GRB 240415B: Swift-XRT observations
  51. GRB 240415A: Swift-XRT refined Analysis
  52. GRB240421B: Zadko Observations
  53. GRB 240421B: Fermi GBM Observation
  54. GRB 240421B: Swift-XRT refined Analysis
  55. GRB240421B: BOOTES-5/JGT optical upper limit
  56. GRB 240421B: J-band upper limits from WINTER
  57. GRB 240421B: Swift/UVOT Upper Limits
  58. GRB 240421B: Enhanced Swift-XRT position
  59. EP240417a: no counterpart detection by SOAR
  60. EP240420a: Xinglong decaying optical counterpart
  61. GRB 240421B: Swift detection of a burst
  62. EP240420a: Nanshan optical counterpart observations
  63. EP240420a: GWAC-F50A optical upper limit
  64. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  65. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  66. EP240420a: NOT optical counterpart candidate and potential host
  67. GRB240419A: Skynet Optical Afterglow Analysis
  68. GRB240418A - Candidate afterglow from NIRES
  69. GRB 240419B: Swift/UVOT Upper Limits
  70. EP240420a: EP-WXT detection of a fast X-ray transient
  71. GRB 240419A: Swift/UVOT Upper Limits
  72. GRB 240419B: Swift-XRT refined Analysis
  73. GRB 240419B: optical afterglow from the NOT
  74. EP240414a: Near-IR observations with NIRES and WINTER
  75. GRB 240419B: Enhanced Swift-XRT position
  76. GRB 240418A: Swift/UVOT Upper Limits
  77. GRB 240419A: REM NIR afterglow detection
  78. GRB 240419A: Swift-XRT refined Analysis
  79. GRB 240418A: Swift-XRT refined Analysis
  80. GRB 240419B: Swift detection of a burst
  81. GRB 240411B: Swift/UVOT Detection
  82. GRB 240419A: VLT optical afterglow detection
  83. GRB 240419A: Enhanced Swift-XRT position
  84. EP240416a: J-band observations with WINTER
  85. EP240414a: GMG observation
  86. GRB 240419A: Swift detection of a burst
  87. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  88. GRB 240418A: NOT optical upper limits
  89. GRB 240418A: Enhanced Swift-XRT position
  90. GRB 240418A: AKO Upper Limit
  91. GRB 240418A: Swift detection of a burst
  92. EP240417a: EP-WXT detection of a fast X-ray transient
  93. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  94. Improved IPN triangulation of GRB 240411A
  95. EP240414a: GSP detects optical candidate counterpart AT2024gsa
  96. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  97. IceCube-Cascade 240416A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 240415A: Glowbug gamma-ray detection
  99. GRB 240414A: Glowbug gamma-ray detection
  100. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification

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