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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
Advanced Search

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.

Advanced Search Examples (click to copy):

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

27281 results found.

  1. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  2. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  3. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  4. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  5. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  6. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  7. GRB 240425A: Fermi GBM Final Real-time Localization
  8. Fermi trigger No 735697285: Global MASTER-Net observations report
  9. GRB 240419B: Swift-BAT refined analysis
  10. GRB 240421B: Swift-BAT refined analysis
  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: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  18. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  19. GRB 240421B: GRBAlpha detection
  20. IceCube Alert 240424.08: Global MASTER-Net observations report
  21. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  22. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  23. GRB 240419A: Swift-BAT refined analysis
  24. GRB 240418A: Swift-BAT refined analysis
  25. LIGO/Virgo/KAGRA S240423br: Retraction of GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  27. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  28. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  29. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  30. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  31. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  32. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  33. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  34. Fermi trigger No 735470374: Global MASTER-Net observations report
  35. GRB 240414A: LBT optical detection
  36. GRB 240419B : MITSuME Akeno optical upper limits
  37. GRB 240415A: Swift-XRT refined Analysis
  38. Fermi GRB 240422A: Global MASTER-Net observations report
  39. GRB 240422A: Fermi GBM Final Real-time Localization
  40. GRB240421B: Zadko Observations
  41. Fermi GRB 240421B: Global MASTER-Net observations report
  42. Swift GRB 240421B: Global MASTER-Net observations report
  43. GRB 240421B: Fermi GBM Observation
  44. GRB 240421B: Swift-XRT refined Analysis
  45. GRB240421B: BOOTES-5/JGT optical upper limit
  46. GRB 240421B: J-band upper limits from WINTER
  47. GRB 240421B: Swift/UVOT Upper Limits
  48. Fermi GRB 240421A: Global MASTER-Net observations report
  49. EP240417a: no counterpart detection by SOAR
  50. EP240420a: Xinglong decaying optical counterpart
  51. GRB 240421B: Swift detection of a burst
  52. EP240420a: Nanshan optical counterpart observations
  53. GRB 240421A: Fermi GBM Final Real-time Localization
  54. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  55. EP240420a: NOT optical counterpart candidate and potential host
  56. Fermi trigger No 735280430: Global MASTER-Net observations report
  57. GRB240419A: Skynet Optical Afterglow Analysis
  58. GRB240418A - Candidate afterglow from NIRES
  59. IceCube Alert 240419.98: Global MASTER-Net observations report
  60. GRB 240419B: Swift/UVOT Upper Limits
  61. EP240420a: EP-WXT detection of a fast X-ray transient
  62. GRB 240419A: Swift/UVOT Upper Limits
  63. GRB 240419B: Swift-XRT refined Analysis
  64. GRB 240419B: optical afterglow from the NOT
  65. LIGO/Virgo/KAGRA S240420aw: Retraction of GW compact binary merger candidate
  66. Swift GRB 240419B: Global MASTER-Net observations report
  67. Swift GRB 240419A: Global MASTER-Net observations report
  68. GRB 240418A: Swift/UVOT Upper Limits
  69. GRB 240419A: REM NIR afterglow detection
  70. GRB 240419A: Swift-XRT refined Analysis
  71. GRB 240418A: Swift-XRT refined Analysis
  72. GRB 240419B: Swift detection of a burst
  73. GRB 240411B: Swift/UVOT Detection
  74. Fermi trigger No 735089036: Global MASTER-Net observations report
  75. EP240414a: GMG observation
  76. GRB 240419A: Swift detection of a burst
  77. GRB 240418A: NOT optical upper limits
  78. GRB 240418A: AKO Upper Limit
  79. GRB 240411A: GOTO early optical upper limits
  80. Swift GRB240418.85: Global MASTER-Net observations report
  81. GRB 240418A: Swift detection of a burst
  82. EP240417a: EP-WXT detection of a fast X-ray transient
  83. Fermi GRB 240417A: Global MASTER-Net observations report
  84. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  85. GRB 240417A: Fermi GBM Final Real-time Localization
  86. GRB 240415B: GECAM-B detection
  87. EP 240416a: Xinglong and NOT decaying optical counterpart
  88. GRB 240415A: Swift-BAT refined analysis
  89. EP240416A: MASTER optical observations
  90. GRB 240414A: Swift-BAT refined analysis
  91. EP240416a: Kinder optical counterpart candidate
  92. EP240416a: EP-WXT detection of a fast X-ray transient
  93. GRB 240414A: AbAO optical upprer limit
  94. GRB 240415A: Swift/UVOT Detection
  95. GRB 240415A: Fermi GBM Observation
  96. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  97. GRB 240414A: GMG observation
  98. EP240414a: EP-FXT follow-up observation
  99. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  100. GRB 240415A: OHP/T193 optical observations

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