As we have seen, not all excavations follow the same archaeological standards in the field. Different excavation techniques affect the quantity of coins found at synagogue sites. For example, sifting the soil will yield more small coins than excavating with pickaxes and trowels. The use of a metal detector can also help to find more metal objects. For our research specifically, it is further important that the archaeologist took detailed field notes: we need to know if the coins were found on top of the floor, immediately underneath it, or deep in the foundations, as this changes their function. Were the coins found close to each other or were they spread out over a large area? In the case of a stone slab floor, were coins found between the stone slabs or only underneath them? Small differences in the context of a deposit can have a huge impact on its final interpretation. The lack of images of these deposits in published reports, moreover, makes it impossible for researchers to re-examine the finds, their contexts, and their arrangement. Furthermore, the final excavation report should mention also if the entire floor was excavated or only parts of it. Is this the total assemblage of coins at the site or can we expect there are more coins under other parts of the floor?  Were the coins found under a sealed patch of the floor or did the archaeologists only excavate areas where the floor was missing, which could make the coins intrusive? Did the archaeologists check under or behind the benches or were these not lifted? How far did they dig inside the bemah in those cases where the structure had fill in it? Were there visible layers inside the bemah and did they receive different locus numbers? When a coin deposit was found, were there other objects close by, like nails or pieces of organic material that might indicate a container?
As the reader can assume from the above list, most synagogues have not been excavated according to these standards and most published synagogue deposits do not mention all the details required for an objective comparison between deposits. When it comes to publishing especially, archaeologists need to make hard decisions: what should they included and what not? Preference in the past was mostly given to an historical and architectural overview of the site, complemented by maps and plans. The publication reports generally highlight important finds like unique objects and focus on material that can date the different stratigraphical layers. Depending on the particular goal of the excavation project, more or less attention will then be given to the smaller finds, including the coins. A painful example is the (short article) publication of the Qasrin excavations from 1988, in which Zvi Ma’oz and Ann Killebrew only mention that “120 small bronze coins” were found, the latest of which date to “the reign of the Byzantine emperor Anastasios I, who ruled from 498 to 518 CE.” The excavations were conducted in the 1970s, but no further information on the coins has ever been published.
When a coin chapter is included, the quality and detail of the coin catalogues can also vary widely. In the publication of the bronze coins found in a vessel in the synagogue at Gush Halav, for example, Joyce Raynor states that only 417 of the 1953 coins could be sufficiently cleaned to permit identification. For these coins she provides an approximate date, and she also mentions some examples of types within the group. However, no sizes, weights, minting origin, or descriptions of obverse and reverse sides of any of the coins are provided. In the final report on the synagogue at Horvat Kanaf, Donald Ariel published several useful tables. One mentions all 523 coins discovered in the building and organizes them by locus. The IAA registration number and date are also provided for each coin. In another table, the coins are grouped by date and the minting origins within the group are given. However, it is impossible to correlate the coins within each group to their minting places. Furthermore, none of the tables mentions sizes, types, or weights of the coins. The chapter ends with photographs and full description of some coins, but this is limited to only 16 of the 523 specimens.
These missing or incomplete coin reports make it impossible to obtain an accurate picture of the contents of coin deposits found in ancient synagogues based on published information. Furthermore, incomplete tables make it impossible to compare deposits or to apply statistical analysis on the different groups. Any research project focused on excavated coins is thus impeded by the incomplete data published in excavation reports. To take account of this situation and to obtain as much data as necessary for setting up a meaningful database for comparison and interpretation, the following steps below were taken by me.
According to Israeli law, all antiquities found in the State of Israel become the property of the state and must remain in the country. All coins discovered during excavations are generally stored in the Coin Department of the Israel Antiquities Authority, where one can consult them with permission from the IAA. Access to the coins, however, can be obstructed because of copyright laws: archaeologists holding an official excavation license from the IAA have exclusive publication rights over the excavated finds for thirty years. Only after that do archival materials become available publicly. Thus, if somebody wants to publish material before then, official permission from the excavators must also be sought.
In the fall of 2019, I travelled to Israel/Palestine to access the IAA Coin Department’s online database and obtain full records on (almost) all the analyzed coins from excavated synagogues. Thus, this project provides a complete overview of all (non-stray) coins found in ancient synagogues deposits. Furthermore, interviews with the original excavators gave me a better understanding of the contexts of the deposits, and many archaeologists shared with me photographs and images that had never been published. Unfortunately, I was still not able to collect every piece of information that may have been desirable. Many archaeologists who excavated the synagogues, for example, have passed away and their archives are lost. Other specialists I contacted never replied. Others refused to share their numismatic reports before final publication or could only provide partial information. Furthermore, publishing houses like the Israel Exploration Society did not give me permission to reproduce images from their book series for my website. All these limitations made building a database of coin finds a challenging endeavor. I have attempted to assemble as much information I could find on every coin deposit, including looking at pictures and field notes in the archives, and talking to excavators, but it should be clear that this project is not, and can never be, clear-cut and complete.
Finally, there are at least two recently excavated synagogues in which coin deposits have been found that could not be incorporated in this database. The first is located at Umm el-Qanatir in the Golan, excavated since 2003 by Yehoshua Dray, Ilana Gonen, and Chaim Ben-David. Here, 7466 coins were discovered under or in between the pavement stones of the synagogue floor, and under the benches. At the beginning of 2021, however, the coins were still in process of being cleaned by Dray and further analysis had not yet been conducted. The only information known to me is that most coins are bronze, but a couple of gold ones were also discovered. The second building is the synagogue of Arbel in Lower Galilee, currently under excavation by Benjamin Arubas on behalf of the Hebrew University in Jerusalem. This building will be discussed in more detail in chapter Five (“SYNAGOGUE COIN DEPOSITS: THE FLOOR DEPOSITS”) but according to sources I spoke to in 2020, here too recent excavations have discovered large numbers of coins that had previously been overlooked. More details on these coins have not been released yet.
 This was also brought up by Ahipaz 2015, p. 12.
 Even more, my personal experience with the excavations at the Horvat Kur synagogue has shown that there can be differences in the numbers of coins found between sifting with an 18 mm mesh and a 10 mm mesh.
 Especially when it has been decided not to excavate the entire floor. A metal detector can be very useful at the site to make sure you are not missing any (large) coin deposits. I have noted in my catalogue when coins were found through the use of a metal detector (if known). Unfortunately, it is (in most cases) impossible to know if archaeologists were digging with large or small tools, or if all soil from an excavation site was sifted or not, and thus if all coins from each deposit were recovered. In my catalogue, I follow the number of coins as stated by the original excavators in their final publication reports, or (in case there is no report) the number of coins as could be found in the IAA database. It is very likely, however, that many more coins were missed by the excavators.
 Sometimes archaeologists decide to only take out a certain number of pavers to check the soil underneath, or to only excavate patches of a plaster floor where the floor has crumbled. When large amounts of coins are found in these areas, it might be assumed that many more coins are hidden under the rest of the floor and this should be taken into account when making statistical comparisons between sites. Many ancient synagogues, moreover, have floors that are covered with mosaics or decorated stone slabs. Because of this, it is often decided to not dig under the floor but to leave it in place. In such cases, the use of a metal detector could be useful to learn if and where metal objects are still laying under the floor.
 As one can see in the catalogue, many coins were found in places there the mosaic or flagstone pavement was missing, but the bedding was still intact.
 This is especially true for older excavations. For example, the 1932 final publication of the synagogue at Beth Alpha describes the architecture and mosaic floor of the building but does not contain a separate chapter on the coins. The only information we have on the coin finds of this synagogue is mentioned on p. 48: “Only a few ancient articles were found in the course of the excavation. The most important discovery of this kind was a number of bronze coins in the hollow built into the floor of the apse on the south of the synagogue. Thirty-six coins in all were found in the earth which filled up the hollow. Most of them were so worn and defaced that they could not be identified. Only seven had survived in better condition.” (Sukenik 1932).
 Ma’oz and Killebrew 1988, p. 18.
 See Duyrat 2016a, pp. 214–217 and 2016b for an appeal for standardization in coin publications and what that would look like.
 Raynor 1990, p. 243.
 Ariel 2015.
 Permission for the export of certain antiquities can be granted by the Israel Antiquities Authority, but this can be a long and difficult process (https://mfa.gov.il/MFA/PressRoom/1998/Pages/Antiquities%20Law-%201978.aspx).
 Ariel 2016, p. 110. For example, in this project, I was not allowed to publish the 14 Arab-Byzantine coins found at the synagogue of Rehob in 1974 since the excavators are still working on the final publication of the site.
 For how coins from archaeological excavations are stored and managed in Israel, see Ariel 2016.
 There might also be a third: the synagogue at H. Natur in the Upper Galilee. This synagogue has not been excavated, but oral testimonies attest that over the years residents of nearby settlements have collected thousands of coins from the site. Some members have reported and delivered 365 coins of those to the IAA, who have identified 199 of them; they can be dated to 425-450 CE. According to the members, the coins came from below the floor level (Ahipaz and Leibner 2021, p. 219, n. 27; Ilan, 1991, p. 33 (Hebrew); Yosef Stephanski, Rosh Hanikra Survey Map, Site 196: http://survey.antiquities.org.il/#/MapSurvey/2/site/535 (Hebrew)).
 Dray, Gonen and Ben-David 2017, p. 216, p. 225: the coins were scattered all over under the floor, forming a sort of “carpet” of coins.
 Personal communication Yehoshua Dray.
 Personal communication Chaim Ben-David. Gold coins as part of a scattered “coin layer” under the floor would be very unusual. The fact that the synagogue has been dated to the late 6th century would also make this the youngest example of the phenomenon. The uniqueness of this site will be important for further research into this topic.
 Hundreds of coins from this site had already been collected over the years before the renewed excavations, see Dolev 1988. Approx. 500 have now been found in several groups under the floor in the renewed excavations (Ahipaz and Leibner 2021, p. 219, n. 31). I tried several times to get in contact with Arubas through email and phone calls, but never received a reply.