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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').

14272 results found.

  1. GRB 240516A ATCA radio observations
  2. IPN triangulation of GRB 240514B (short)
  3. GRB 240511A: Observations from GTC/OSIRIS+
  4. GRB 240516A: Swift detection of a burst
  5. GRB 240511A: radio detection of afterglow candidate
  6. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  7. GRB 240511A: J-band observations with WINTER
  8. GRB 240511A: Enhanced Swift-XRT position
  9. GRB 240511A : MITSuME Akeno optical upper limits
  10. GRB 240511A: Swift-XRT refined Analysis
  11. GRB 240511A: Swift detection of a burst
  12. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  13. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  14. EP240506a: Xinglong optical upper limit
  15. EP240506a: Archival radio searching
  16. EP240506a: TRT optical upper limit
  17. EP240506a: Optical upper limit with Kinder observations
  18. IPN triangulation of GRB 240504A
  19. GRB 240502A: 1.3m DFOT Optical upper limit
  20. EP240506a: EP-WXT detection of a new fast X-ray transient
  21. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  22. GW170817: VLA observations at ~5.5 yrs since merger
  23. GRB 240415A 1.3m DFOT Optical upper limit
  24. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  25. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  26. Fermi-LAT gamma-ray observations of IceCube-240424A
  27. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  28. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  29. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  30. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  31. EP240426b: AST3-2 optical upper limit
  32. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  33. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  34. EP240426b: EP-WXT detection of a new fast X-ray transient
  35. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  36. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  37. XMM-Newton observation of EP240426a
  38. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  39. GRB 240414A: NOEMA detection
  40. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  41. EP240426a: GMG optical upper limit
  42. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  43. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  44. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  45. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  46. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  47. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  48. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  49. GRB 240422A: Glowbug gamma-ray detection
  50. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  51. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  52. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  53. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  54. LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts
  55. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  56. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  57. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  58. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  59. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  60. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  61. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  62. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  63. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  64. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  65. LXT240402A/GRB240402B: Chandra X-ray detection
  66. GRB 240419A: Possible ATCA radio detection
  67. GRB 240421B: ATCA radio observations
  68. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  69. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  70. GRB 240421A: Glowbug gamma-ray detection
  71. GRB 240414A: radio detection with the VLA
  72. GRB 240414A: AMI-LA radio observations
  73. GRB 240414A: LBT optical detection
  74. GRB 240419B : MITSuME Akeno optical upper limits
  75. GRB240421B: Zadko Observations
  76. GRB 240421B: Swift-XRT refined Analysis
  77. GRB 240421B: J-band upper limits from WINTER
  78. GRB 240421B: Swift/UVOT Upper Limits
  79. GRB 240421B: Enhanced Swift-XRT position
  80. EP240417a: no counterpart detection by SOAR
  81. EP240420a: Xinglong decaying optical counterpart
  82. GRB 240421B: Swift detection of a burst
  83. EP240420a: Nanshan optical counterpart observations
  84. EP240420a: GWAC-F50A optical upper limit
  85. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  86. EP240420a: NOT optical counterpart candidate and potential host
  87. GRB240419A: Skynet Optical Afterglow Analysis
  88. GRB240418A - Candidate afterglow from NIRES
  89. GRB 240419B: Swift/UVOT Upper Limits
  90. EP240420a: EP-WXT detection of a fast X-ray transient
  91. GRB 240419A: Swift/UVOT Upper Limits
  92. GRB 240419B: optical afterglow from the NOT
  93. GRB 240419B: Enhanced Swift-XRT position
  94. GRB 240418A: Swift/UVOT Upper Limits
  95. GRB 240419A: REM NIR afterglow detection
  96. GRB 240419B: Swift detection of a burst
  97. GRB 240411B: Swift/UVOT Detection
  98. GRB 240419A: VLT optical afterglow detection
  99. GRB 240419A: Enhanced Swift-XRT position
  100. EP240416a: J-band observations with WINTER

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