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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').
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"
  1. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  2. GRB 240715A: Swift/UVOT observations of the XRT sources.
  3. GRB 240715A: Swift-XRT observations
  4. GRB240713A: Swift/UVOT Upper LImits
  5. EP240708a: X-ray follow-up observations with Swift/XRT
  6. GRB 240715A: GECAM-C detection of a short burst
  7. Konus-Wind detection of GRB 240715A
  8. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  9. GRB 240713A: Swift-XRT observations
  10. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  11. GRB 240712A: Swift-XRT refined Analysis
  12. SVOM/GRM In-Flight Trigger of GRB 240715A
  13. GRB 240713A: LAST optical upper limit
  14. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  15. GRB 240715A: Swift ToO observations
  16. Fermi GRB 240715A: Global MASTER-Net observations report
  17. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  18. GRB 240715A: Fermi GBM Observation
  19. GRB 240712A ATCA radio observations
  20. GRB240715A: GRANDMA Optical Upper Limits
  21. IPN triangulation of GRB 240715A (short)
  22. GW s240422ed: Swift UVOT follow-up
  23. GRB 240712A: Swift/UVOT Upper Limits
  24. EP-WXT flaring star and the optical flaring activity during its decay phase
  25. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  26. The EP-WXT source triggered on July 14th is likely a flaring star
  27. GRB 240715A: Fermi GBM Final Real-time Localization
  28. GRB 240713A: Tiled Swift observations
  29. GRB 240713A: J-band upper limit from WINTER
  30. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  31. GRB 240713A: JinShan optical upper limits
  32. GRB 240713A: OHP/T120 optical upper limit
  33. GRB240713A: X-ray follow-up observation with EP-FXT (duplicate submission of GCN 36859)
  34. GRB240713A: X-ray follow-up observation with EP-FXT
  35. GRB 240713B: AstroSat CZTI detection of a long burst
  36. GRB240713A: Optical upper limit with Kinder observations
  37. Fermi Sub-threshold Observation of GRB240713A
  38. GRB240713A: TAROT and GRANDMA Observations of SVOM/ECLAIRs GRB240713A
  39. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  40. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  41. EP240708a: GSP optical upper limit
  42. GRB 240712A: Swift detection of a burst
  43. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  44. GRB 240711A: Fermi GBM Final Real-time Localization
  45. Fermi trigger No 742405878: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  47. Fermi trigger No 742317942: Global MASTER-Net observations report
  48. EP240708a: KAIT optical upper limit
  49. Fermi GRB 240710A: Global MASTER-Net observations report
  50. GRB 240710A: Fermi GBM Final Real-time Localization
  51. EP240708a: NOT optical observations
  52. EP240708a: SVOM/C-GFT optical upper limit
  53. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  54. EP240708a: Optical upper limits with Kinder observations
  55. EP240708a: EP-WXT detection of a fast X-ray transient
  56. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  57. EP240703b: GSP optical upper limit
  58. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB
  59. GRB 240705A: Fermi GBM Final Real-time Localization
  60. EP240703b: TRT optical upper limits
  61. EP240703a: TRT further optical observation
  62. EP240702a: TRT optical upper limits
  63. Konus-Wind detection of GRB 240627A
  64. IPN triangulation of GRB 240628B (short)
  65. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  66. EP240703a and EP240703b: Swift/XRT upper limits
  67. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  68. EP240703a: KAIT optical upper limit
  69. EP240703a: BTA observations
  70. EP240703c: Kinder optical follow-up and Swift XRT observations
  71. EP240703a: BOOTES-3 optical upper limit
  72. EP240703a: Liverpool Telescope optical follow-up observations
  73. EP240703a/GRB 240703A: TRT optical candidate likely not real
  74. EP240703a: Kinder optical follow-up observations
  75. EP240703c: EP-WXT detection of an X-ray transient
  76. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  77. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  78. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  79. IPN triangulation of GRB 240627A
  80. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  81. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  82. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  83. EP240703b: EP-WXT detection of a fast X-ray transient
  84. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  85. EP240702a: Swift/XRT upper limit
  86. EP240703a: EP-WXT detection of a fast X-ray transient
  87. EP240702a: GSP optical upper limit
  88. The first three GRBs detected by SVOM: GRB 240627B, GRB 240629A and GRB 240702A
  89. GRB 240702A: BALROG localization (Fermi Trigger / GRB 240702885)
  90. Fermi GRB 240702A: Global MASTER-Net observations report
  91. GRB 240702A: Fermi GBM Final Real-time Localization
  92. EP240702a: EP-WXT detection of a fast X-ray transient
  93. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  94. Fermi Gamma-ray Burst Monitor trigger 741448122/240630575 is not a GRB
  95. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  96. Fermi trigger No 741448122: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S240630t: Updated Sky localization
  98. LIGO/Virgo/KAGRA S240629by: Updated Sky localization
  99. LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations

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